Introduction: Winterised Flip-Flops

Jack Frost's been pricking at my toes. Here illustrated as a cactus, it's hard to photograph cold at short notice. Anyways it's not a problem any more, my toes-icles are warming nicely in my very first pair of hand-made custom-fit shoes. There is nothing quite like the comfort of shoes made to fit, I highly recommend it to everyone with feet.
I'll definitely make several more pairs of these now I know how and I look forward to trying out different fabrics, prettier and more hard wearing but as prototypes (and my first attempt at making any kind of footwear) my main concern was not wasting money as well as time, so I restricted myself to only using materials and tools I already had. So for fabric I used a flannel shirt, just the sleeves, leaving the vest part intact and still wearable, but I'll most likely use it in some other project. For the soles of the shoes I used flip-flops (or thongs or whatever they're known as wherever you're reading this, they're both ridiculous names for what is a ridiculous excuse for a shoe) Between the outer and lining layers of fabric there is a nice thick layer of quilt batting; this is the secret to fooling ones feet into believing that they're still wrapped up in a duvet all day long, which on a cold day is exactly where they want to be. The batting I used was easily procured from a old pillow, with most cushions, pillows, and duvets it's possible to open the seams, peel back the cover and carefully separate the layers inside. Alternatively you could use several layers of old jumpers, blankets, or towels. Or you can go out and purchase quilt batting at a sewing supplies shop.
Any one reading this and contemplating making a pair for yourself I recommend making a rough pair like these just to establish a pattern that suits you then start thinking about using more attractive/ appropriate (expensive) materials for the the outer shell, I've found the flannel is suitable for a lining fabric, but also fleece or fake fur could be a great for extra warmth and comfort. I hear it's possible to waterproof fabric shoes with liquid latex or other paint on treatments, I haven't tried that yet.
If you find yourself without a pair of flip-flops but still want to sew your own shoes (like I am right now, those were my only pair) at the end I show how I took apart an old pair of hideously ugly boots to salvage the soles, those will be the base of my next project.
I believe the method I use here could be applied to making and attaching shoe uppers to any type of sole, for example high-heel shoes, or running shoes, and I intend on testing this theory in the near future.

Step 1: What I Used

we're building shoes from the ground up
Soles: Flip-Flops    (alternatively you may wish to salvage soles from an existing pair of shoes, refer to last step to see example)
Lining for Soles: I cut mine out of a strip of flannel around 17inches (44cm) long, and 11inches (28cm) wide.
Batting for shoe liners: 8x10in (21x26cm) I didn't use any in this example, but it can be easily added if extra cushioning is desired.
Upper Part of the shoe:
Fabric of choice  - I used approximately 20x30 inches (52x77cm) that's sufficient for the outer shell and the lining, if you wish to use two different materials you'll need about 20x15 inches (52x38cm) of each.
Batting, I cut mine out of a piece about 20x10inches (52x26cm) and about 1.5 inches (4cm) thick.
   
When referring to these measurements consider that my finished shoe is 10in / 25cm long, 3.25in / 9cm wide. I am given to  understand this is a ladies size (5-British) (38-European) (8-American) (24-Japanese)  Adjust your measurements accordingly.


Sewing Supplies:
Measuring Tape
Tailors Chalk (or something else to mark fabric with)
Tacking Pins
Needle and Thread
Scissors
Thimble

Hardware:
Push Pins
Ruler
Scalpel
Pliers
Staple Gun and Staples (I used around 24 in total)
Hot Glue Gun & Glue Stick (I used about 4 inches of glue)
Fabric Glue I used only a tiny amount of this, you could probably use hot glue OR fabric glue, it may not be necessary to use both.
Iron
Paper I used 1-2 sheets of A4 printer paper, you may find graph paper helpful, newspaper would be fine too.
Sticky Tape (masking tape, sellotape or similar)
Pen (a sharpie or similar)

Step 2: Flip-FLop

Transform the flip-flops into usable soles, so I can now stop using that word. One last time, with feeling  _Flip-Flop_ that's it, it's lost all meaning to me.

Use a scissors or a scalpel and carefully remove the straps a little way above the sole.
Mark a line with a pen the point where the plug of the strap is flush to the sole, then pop out the plugs, it may be important to note which plug goes where depending on how they're set in, you'll want them to fit back in snugly to keep your shoes watertight.
Using a scalpel level off the the plugs where your mark indicates, make the cut reasonably horizontal if possible.

I used a little craft paint brush to clean out the hole before gluing in the plugs in place, it's a good idea even if they're new to ensure good contact between surfaces, you don't want these popping back out while strutting down the street.
I used and would happily recommend Loctite hot melt  glue, seems to hold up to weather and wear. I'm sure there's plenty of other glues that would also work well. Suggestions?
Any glue that wells up can be gently tapped flush as it cools.

Step 3: It's a Fine Line(ing)

This type of lining can be made and applied to existing shoes. Or you may decide to skip this step entirely and it wont effect the appearance of the finished shoe, but lining is a good way to get some extra warmth and cushioning in your shoes.
Get out the fabric you intend to make the lining out of.
Ironing out any wrinkles and creases now will make everything go much easier. Where you have a straight line in a pattern (any pattern, not just here) it's a good Idea to align it to the grain of the fabric, it helps keep everything from twisting and is particularly important if you're using patterned fabric, and want your shoes to match.
Using tailors chalk (or what ever you have to mark your fabric with) trace out 4 sole shapes - 2 upper liners and 2 lower liners. When marking and cutting I leave a 0.75in / 1.5cm seam allowance.
The upper piece will be the finished inside of the shoe, so it might be a nice idea to use fleece or fake fur, the lower piece will be glued to the sole and will be unseen in the finished shoe so could be made from cheaper fabric or a water proof or thermal insulating material.
If you want even more warmth and padding you can also trace the same sole shape in quilt batting, I didn't feel like this step was necessary for me as these soles are already particularly comfy, but I'll explain how it's done, when you're cutting the batting or whatever other material you sandwich in here) there's no need to allow for a seam allowance as you would with the fabric lining pieces, just cut very slightly on the inside of the line dictated by the soles.

Once you've got the pieces cut out pin 2 lefts together, (rite sides facing)  and pin 2 rights together (rite sides facing) sew all around but leave a gap big enough to turn the lining right way round, usually about 4in / 10cm is sufficient, allow a larger opening if you intend on fitting in quilt batting (6in / 15cm) It's a good idea to do this on the outside straight edge of the piece, as you will need to top stitch later and it's easier to top stitch on the straight. If you're using a Sewing Machine be sure to back tack a few stitches  at the beginning and the ends.

Cut some little triangles out of the curves at the toe and heel,  be careful not to cut too close to the line of stitching and handle the piece gently until it's secured with top stitching.

Turn the linings rite way out and pin down ready to top stitch, if your putting in batting slip it in now, pin the opening closed and top stitch all around.

Quilting: this step is really only necessary if you're using batting. After you've top stitched all round the outside you'll want to lock the 3 layers (top of lining, batting, bottom of liner) together. You can do this by sewing some kind of pattern through the piece, this can be random, follow the contours of your foot or follow the pattern of the fabric, I just followed the lines in my fabric.

Lining complete, now attach to sole. There's likely a dozen good ways to attach the linings to the soles, I'd be happy to hear suggestions of preferred methods. Here's how I did it:
I applied a thin layer of fabric glue to secure the lining to the sole in the center and used hot glue all round the edges. The glue I use stays slippery for some time before it dries so I  was able to play with the fit. I tacked the linings on to the soles using Push Pins,  mine were a perfect fit, all going well yours should be too. Once I was satisfied they were in the right place I removed 1 pin at a time and ran a small bead of hot glue along that area about 1cm from the edge and patted the lining down to it.

*TIP*
Here's my top tip for using hot glue on fabric,  working this way you'll find you use much less glue and you don't have to risk sticking your fingers to scalding hot glue:  just apply a thin bead and allow to fabric to adhere lightly to it. Once the piece is glued down and you've removed all the pins take out your Iron and set it to a low heat, just warm enough to melt any pockets of glue when you iron the whole piece all the glue will soften enough that the fabric will adhere to it and when it cools it will be secured.
Be careful not the apply too much heat or too much pressure so the whole thing doesn't slide off in a horrible sticky mess.
If you are too heavy handed with the glue it may soak through and leave ugly un- washable stains in your fabric, so go lightly.

That's it. You got Sole. (if you happen also to be a soldier, that's your own business)

If your adding liners to existing shoes I would avoid hot glue entirely and stick to a thin layer of fabric glue, using a brush or roller to apply it evenly to the bottom of the liner and then press it into your shoe. Depending on the type of shoe, tracing around the sole may not give you the shape of the lining. (for example high-heel shoes) Most shoes have some kind of liner in them already and if it's loose you may be able to use it as a template. Otherwise I would trace around the foot itself, round out the toe area, add a little on all sides, and use that as the pattern for the liners, might be worth comparing both feet and using the larger. Also try it in paper first and check that it will fit easily into the shoe before committing to making it up in fabric.

Step 4: On the Up 'n' Up

If any one would like the actual pattern that I used for my uppers I will be happy to upload it. It may be useful to some of you as a reference, for now I think it will be more use to explain how I came up with my pattern so you can make a shoe custom fit to you.

A word about pattern drafting, any pattern, not just this one. If we are drafting for a human, in all our many splendid shapes and sizes and... contours...  the one commonality we all share is that no where on our bodies will you find a straight line. No really, you go ahead and look, I can wait.
See?
So the very first thing I do is to establish an (imaginary) straight line to work from, then send out the feelers and look for the edges. (It's a good strategy for jigsaw puzzles and it may be applied here also) This line will usually form part of a seam in the finished garment, though it doesn't necessarily remain straight, but don't worry about that for now.
If you want the thing to fit well you don't want to whack down an arbitrary straight edge, you want to delineate a point of symmetry or articulation. Set aside for the moment trends, or what u think you want the end result to look like. Consider first, if you would the human - we are alive, we move around, we're supported by skeletal armatures, there are complicated mechanical bits and musculature, and then there's the fleshy bits and it's all suspended in liquid wrapped up in a delicate membrane (skin), it's all moving and changing shape all the time, and I think it is this movement and how we move that should be the first consideration when approaching the pattern making process.
Now a foot is not symmetrical, particularly around the toes, so it's not much use drawing a line down the middle of the foot length-wise. I don't usually think of the foot as an especially articulated part of the anatomy, not when compared to say a hand, which easily bends all the way into a fist, but when I took the time to actually notice how I walk I saw that even feet damaged from ill fitting and inappropriate footwear are still extraordinarily flexible, particularly across the arch and especially the toes; a fact which most shoes I've worn appear to take no account of. I determined that I would take account of it, so rather than making shoes that would be trendy or even attractive I allowed the shape, and range of motion of my foot to identify what was needed in a shoe. I'm not suggesting that this style or design is the best answer but it's my start towards finding it. I wish to clarify I am not deluded enough to believe that these shoes are attractive. These are ugly shoes, they have no shelf appeal, at all; unless you are pathologically attracted to ugly shoes. These are, some one might argue, the shoe equivalent of that one guy at the party with a personality, they are a refreshing experience. They fit.

The second image for this step shows a teeny doodle in a notebook lame*nting a cheap (as distinct from bargain) and shoddily** assembled pair of shoes, they looked good, but everything about them was wrong, (you might say they were cobbled*** together, of course I won't say that, but you might.)  and that doodle is really all I had to go on when I began, I have no experience making shoes, did no research and received no tuition, this was pure speculation I wanted to find out if it could possibly be as simple as I imagined, nay fantasied! (alright, steady on)  Turns out -  it is. I set about measuring what I consider to be the crucial measurements of my feet, the places that ill-fitting shoes get wrong. It's likely that these areas will differ for many other people, so have a think about your own feet and what you require in a pair of shoes.

To begin with I marked a line across the width of my foot. The best way of describing where that line is located across my foot is to say that when I wrapped a strip of fabric - an analog for a seam - around that point it felt unobtrusive, it didn't restrict any motion my foot might make, although I knew at that time that a line that curved as it passed over the top of my foot would be an even better fit I made a note of that, so I could add the curve in later. After I had established that straight edge to work from I took all the measurements of my foot from that line, plotting it all out it on a piece of paper as I went along. The main image for this step shows the pattern I arrived at. Each info box on that image describes a key point of measurement of the pattern, it should make sense if you hover over and read the pop-ups; I'll give more detail here as it's something of a game editing multiple boxes.
The shape on the left of the image, top down.
1/ This line (and the corresponding at the bottom of the image) is part of a seam that connects to the the line at the top right of the image.
2/ The length from the sole at the tip of my little toe to the intersection of my arch - anyone who's ever spent a day in heels will not ask why this would be of concern
3/ The width and curve between big and little toes - I don't believe I have ever worn a pair of shoes that got this right before. This line may not be pretty, but damned if ain't comfy. Because I have a curve above these toes and the curve is not attached to anything I was able to make the following short cut to finding this angle - step on it. I'd already measured and marked all the other edges so I put the paper pattern piece on floor stepped onto it and eye balled where my toes fitted in, allowing a similar margin as indicated from the big and little toes already marked, If the open curved area were straight or attached to another seam the pull from the toes would be apparent, as it is this slight tension serves to accentuate the line of the curve.
4/ The desired depth of curve - I had decided earlier it would be desirable to have a curved line here,  but also an aesthetic decision, (refer to 3/ above)
5/ The length from the sole at the tip of my big toe to the intersection of my arch - this measurement would be particularly important if I were making uppers for high-heel shoes, but even in flats it's nice to have the right amount of space.
6/ The width across arch / the width of the foot - articulation. This was the original straight line I drew to make all my other measurements from

The shape on the right side of the image - I mirrored this for the both sides of each foot.
1/ The desired height of the side of the shoe where it connects to the intersection of the arch, which in turn informs the width of the  curve
2/ The length from center back of foot to intersection of arch - flexibility, for example allows for comfortably standing on tip-toes
3/ This line is the measurement from the top back of the foot (ankle) to the beginning of the curved line at the top of the foot, it's important to make this sufficiently snug so the shoe does slip off when walking, less of a problem with stiffer fabrics, with soft fabrics elastic will help. If I was planning on having straps or buckles or eyelets (for laces) I would plot that in at this stage but I decided that for this first pair of shoes I would make a pair of simple soft flats, without any embellishments or hardware, I was focusing on how to construct an upper that would fit.
4/ The height of the back of the shoe, from sole to top of ankle, should not be so high that limits mobility or so low it slips off, this is my preference, you may have other ideas.

Draw the shapes your measurements describe, you may find graph paper helpful, your shapes may look nothing like mine, if you find that this is the case that's great, I'll be willing to bet your feet look nothing like mine either. When you've come up with actual size drawings of the shapes you suspect represent your desired "foot sheath" cut them out and stick it together with some tape, so you can see it in 3d, and try it on. Don't fuss about getting it perfect just trust your measurements, mock it up, see how it fits and then adjust accordingly.

When I was making my pattern I did measure each foot separately, and although my feet are not a perfectly matched pair I decided to make both shoes mirror images of each other; for me the variance was so slight that I was able to merge the the two in favor of the bigger measurements. I also mirrored the the left/right sides of each foot (the pattern piece on the right side of the first image) this may not be suitable for everyone but it works well for me, and I wanted this first pair of shoes to be somewhat simple, so if I went wrong I'd be able to see where.
I suspect there's little use trying to achieve millimeter perfect measurements, even if you are confident in your ability to measure, mark, cut and sew seams correct to a tolerance of less than 2mm (more power to ya if you can) even then there's no accounting for the way feet swell between heat and cold and standing or at rest (if any body knows of a way of accounting for the way feet swell please let me know, just don't tell me to use stretch fabric, I'm working towards making a pair in leather or Pleather, at any rate talk meteorology at me) I recommend measuring both feet either way and then it's up to you to decide if you want both the same or if you want or need a custom fit tor each foot. I don't believe having them both the same makes it go any quicker when it comes to cutting and piecing together the pattern.

A word about materials and fit:
There's little use in having shoes that are fabulously warm if the fit is so snug that it prevents sufficient circulation, which still results in cold feet. It's equally unsatisfactory to have a pair of shoes so light and breathable that they offer no warmth, or if the fit is so relaxed they're no use for walking. Consider your needs and your materials. Careful measuring now will result in a decent finished project and the pattern you come up with here can be revised and reused for future projects.

Step 5: Constructing the Uppers

Now you've got your pattern, cut it out. place your fabric face down (having it freshly ironed makes it easier to work with) trace around your pattern template/s on the reverse side of your fabric. I allow 5/8th of an inch (1.5cm) seam allowance all the way around each piece, whatever seam allowance you are comfortable working with I recommend being consistent.
You will need to cut out:
1 outer shell for the left foot
1 lining for the left foot
1 outer shell for the right foot
1 lining for the right foot
It's important to label each clearly to avoid confusion especially when using just one fabric.

Because of the way I made my pattern each of the shells and linings were made up of 3 pieces which I then seamed together. I could easily have have retraced my pattern onto one piece of paper and then it would have minimized sewing, but I did not for two reasons. Firstly, cutting out the pattern in one piece would require more fabric and create more waste. I always challenge myself to cut a pattern with the least possible amount of waste, even though this fabric is already re-purposed the next piece wont be and I want to know how much I actually need. Secondly having that seam there actually reinforces the shoe, it makes it stronger because there are more layers of fabric, as it's at a point of wear, (my foot bends at that point) it's good that it's reinforced it helps avoid stretching and creasing in the shoe. I definitely wanted to minimize bulk here so after sewing the seam I opened out the seam allowance from the inside and ironed it flat. You may decide to top stitch here, I didn't this time, it's not necessary. If you decide to line your shoe with an especially thick material such as fleece or fake fur I would recommend cutting your pattern as a single piece so you don't have an overly bulky seam which could be restrictive or uncomfortable. If you are using a patterned material for the outer shell of your shoe and want to avoid disrupting this pattern then you may wish to cut the shell out as one piece.

I highly recommend sandwiching something between the shell and the lining for warmth and also to add body to a very thin fabric. (This won't be necessary if your working in something like leather.) There are lots of materials you could use, I used batting, the kind you'll find in a quilt. This stuff is extremely forgiving and easy to work with, I don't have a lot of experience using it and I got on just fine. For this project I got my batting from a pillow, I'm pretty sure it's the same as you can buy in the quilting supplies section of a sewing shop, just maybe less uniform than if it came fresh off a roll. this layer is about 1.5in (4.5cm) thick, this stuff is easy to work with but you'll want to be careful not to pull or stretch the fibers too much or it will be thin in some areas and bunched up in others, however it is a forgiving material and it's possible to repair any signs of over exuberance, just check that you're satisfied it's sufficiently even before you start cutting your pattern from it, you can use your templates again, or just cut around the shell/linings as I did. Whether you use paper or the material you've already cut to trace around I definitely recommend pinning it down carefully before you begin cutting, this stuff has a way of dissolving if it's not held carefully. Unlike the other layers you won't need a seam allowance for the batting, just cut right on the line.

Once you have all the layers cut out let the assemblage commence.
First get your shell and lining for the right foot and lay together with rite sides facing, and then the shell and lining for the left foot and lay together with rite sides facing. Next pin along the seams that will form the top (opening) of each shoe, and also down the back seam that runs from ankle to heel, on one side of the heel seam adjust your line so you are sewing approximately 0.5cm into the seam allowance (make a note of exactly how far and keep it the same for both shoes) this means that when you sew up the back of the shoe you'll be able to overlap by 0.5cm (or how ever much you've allowed) but the seam you sew will still be right on the center line, with out affecting the over all measurement of the shoe. Refer to pictures to see which seam I mean.
If you didn't have to sew up till now, this is the time to get out your needle and thread, or machine if you have one. Be careful that you have aligned the two layers correctly; you want to be sure that when you sew them together the stitches go right down the middle of the line on both layers. Do this for both shoes. After this you will be top stitching, you may decide against top stitching perhaps you don't like the look of it, in that case I recommend a second row of stitching here on the inside.
Next you turn your work so rite sides face out and pin the two layers together ready to top stitch. I decided back when I was drafting the pattern that I would add some elastic around the opening of the shoe to help keep it snug on top of the foot so that it doesn't slip when walking, you may decide on some other device to keep the shoe on, such as straps or eyelets for laces or, (if you were diligent with your measurements and depending on the materials you make your shoe from) it may not be necessary to add anything. If you are using elastic you can use this row of top stitching to form a casing, measure the width of the elastic to ensure you are allowing enough space for the elastic to be passed through and then top stitch just outside of this measurement. At the time I sewed this I thought that a zig-zag stitch would be appropriate, it's not, it's looks awful, a straight stitch would have been much nicer. I didn't hate it enough to rip it out and re-sew, so I'm living with the zig-zag.

Now that you are working on the outside of your shoe uppers you will want to re-trace the sewing line so it's on the outside too. You might have done this from the start but if using chalk it would likely have brushed off by now and you would have to retrace it either way. Retracing from your pattern now allows you to correct for any less than perfect seaming so far. This outer line also marks the point where the shoe upper connects to the sole of the shoe; the seam allowance is the part of the upper that will be attached to the sole, so it is important that you sew in the right place otherwise all that measuring at the beginning will be somewhat pointless, and you want the finished edge to be as neat as you can make it, so that you will have an easier time attaching the sole binding later. When you're happy you've got the line drawn where it needs to be, take your batting and sandwich it between the shell and the lining, pin all around and sew shut.

Okay, those of you who can think round corners might have noticed something kinda funky here; Because batting is so pliable it didn't occur to me at the time but writing this out now I've spotted something you might need to consider. If you decide to add elastic in the way I described, the casing for the elastic will take up some of the space that would otherwise be occupied by the batting. You should measure the width of the casing and cut away this extra width from the inside edge of the batting to achieve a good fit. It's not really a problem when using batting but if you were using say multiple layers of felted wool from jumpers or blankets for example I imagine it would become all creased and wrinkled, it just wouldn't fit in well. Also if you are using multiple layers of alternative material (other than batting) I recommend tacking the layers together, either by hand or with a sewing machine, just a quick series of long stitches close the edges would be sufficient; especially if you don't intend on quilting.

So now you've got something that looks like a pair of ergonomic travel pillows for twin teddy bears, or a couple of yoke collars for two tiny ponies. If you happen to be satisfied with how they look by all means,  skip the quilting. If, however you are concerned that you wish them to look a lot less like clown shoes, then quilt.
Quilting creates little pockets which traps warm air, If you made liners and quilted them, you're already expert at this and no doubt can't wait to do it again, right? Sure.
If you skipped that step, go back and read it, I'm just repeating myself here, and bound to leave something out. It's really up to you how you quilt, what sort of pattern you follow, though I recommend working that out before you start, if you want both shoes to match. You can quilt by hand or on a machine. If you do use a machine I know you can purchase something called a quilting foot, I didn't use one, I was kind of amazed how much the batting compressed as I was sewing it and my machine had no problem with it at all. I followed the vertical lines in the pattern of the fabric I was using and I find the result is both visually pleasing and effective at keeping my feet warm. However you do yours just don't sew into the casing for the elastic.

Step 6: Elastic (if You're Using It)

The measurement of the length of the elastic casing is correct to the measurement of my foot, allowing for some overlap to sew up the back of the shoe; so I cut a piece of elastic to the same length, less 1 inch, this should result in a nicely secured fit, you don't  want to make it so that the elastic digs in to the foot or effects circulation. you really should pay attention to the type of elastic use happen to be using and how stretchy it is, for example if your elastic is super stretchy you may need to make it 2 or 3 inches less than the length of the casing the get the desired effect. Alternatively at this point you may wish to thread through a length of ribbon or a shoe lace which can be tied in a bow at the back of the shoe, or if you back track a few steps you could easily make an eyelet at the front, or anywhere along the casing so a bow could be tied there, but I chose the elastic.
I attached a safety pin at each end of the elastic, one small pin to guide the elastic though the casing and the second, larger pin to stop the other end from sliding through.

Next you'll need to secure the two end of the elastic together, I did this with a needle and thread. A thimble and pliers may not be necessary, but for a dense elastic such as I was using they definitely save the hands a lot of hurting (if you think I'm a wuss think of a finger pierced by the eye end of a needle) The thimble is to push the needle into the elastic, and the pliers pull the needle the rest of the way through. Without them I would have only been able to stitch into the outer woven covering of the elastic, which is fine if that's all you can manage, but it often causes the ends to fray and come unraveled.

All that remains for your uppers now is to sew up the back of the shoe. You should have made a note of how much overlap you allowed from step 5. In my case it was 2/8th of an inch (0.5 cm), the overlap is hidden inside the shoe and on the outside the seam is sewn into a previous row of top stitching, for the casing I pushed the seam allowance inside the casing and sewed it shut by hand, I think this looks pretty neat.
Alternatively you may wish to make a "pull tab" for the back of the shoe this could be particularly useful if you the back of the shoe looks a mess it also means you can forget about the overlap, just butt the 2 ends together, just touching and whip stitch along to hold them in place then cut out a strip of fabric the height of the back of the shoe, multiplied by 2 (plus 2.5 to 3.5 inches, optional) this strip should be about 1.5 to 2.5 inches wide. Finish the edges of this strip as I describe for the sole binding in step 7, you don't have to sew the edges, but I recommend ironing the strip flat. The prepared strip can then be used to hide the seam at the back of the shoe, inside and outside (and the optional 2.5 to 3.5 inches extra that you allowed when folded over makes a handy tab to pull the shoe on.) If neat sewing is just not your thing DON'T PANIC you could probably get away with gluing this onto the shoe and no one needs to know anything went wrong. In fact it's a nice design addition which you may well decide on deliberately. I hope this description makes sense, if not leave a comment and I'll post some pics to illustrate it.

Step 7: Attach the Upper to the Sole

You got uppers and you got soles, get them together and you got shoes. I used push-pins to tack mine on, the soles I used were soft enough that I could do this with no damage at all, I advise being sympathetic to the materials you're working with, if push pins might damage your soles then don't use them, find some better way of doing it. At any rate once I had manipulated the uppers on to the sole I was able to try my shoes on for fit, being careful to avoid any tack in toe missteps. Now if the soles you used were a good match for your feet, and all the measurements you took when making your pattern resulted in an upper that is also a good match for your feet, then it follows that these should want to fit together, but you may need to persuade them a little. I began at the back and worked my way forward. My advise is whatever you do to one shoe, do the other the same, and they should work out really well.
Once you've checked the fit and you're happy with it, (like incredibly super happy, these should be the best fitting pair of shoes ever!) you can start taking out the tacks one at a time and securing small sections with hot melt glue (or fabric glue) I went into a fair amount of detail when attaching the liners to the soles, so if you skipped that go back and read it now, seriously, there's some good advice in there. If the fit is not quite as super amazing as you would have hoped when you first try the shoes on, you have the whole seam allowance to play around with so pop out the tacks in whatever area/s that's causing trouble and make your adjustments, don't forget to make a note of it so you can adjust your pattern for future projects.
After I had everything glued in place I went around the shoes with my staple gun, I especially recommend this is you're using a fabric glue that takes a long time to dry and tends to slip around a lot, the staples will secure everything till the glue dries. If you have no glue you may be able to just use staples. I did it because I find a lot of my flat shoes tend to tear apart, soles from uppers, and having just tried these shoes on for the first time and realizing how well they were turning out I decided I would want to wear them and I wanted them to last. When using staples make sure you angle the gun slightly towards the bottom of the sole, away from where your foot will be, and don't put a staple too close to the edge of the sole, somewhere near the middle and angled down is ideal.

One last finishing step and you're shoes are complete: make a binding for the soles.
I made my binding out of the same fabric I used throughout the shoe, no particular reason, continuity I guess. Almost any other material you can think of would have been more suitable. Maybe I was trying to stop myself from ever wearing them outside; in spite of how proud I am of how they turned out these are ugly shoes, made from ugly fabric if I had put on a binding that would have held up to being worn out in the rain and stayed water tight I would have worn them out and teamed them with shirt printed with an arrow pointed down that says "I made these!" The flannel binding means they are just fine for indoor shoes, (or driving shoes, keep them in the car and swap heels for these, to drive in.)

Whatever material you decide to make your binding out of get it out and follow these steps:
Measure around the sole of the shoe, add an inch for overlap, (depending on material you may not want it to overlap, but I would still cut a little extra, then trim to fit when attaching it to the shoe) measure the height of the sole of the shoe / how high you want the binding to go, if you are using something like rubber, or leather you wont need to finish the cut edges, if you're using a woven fabric, like I did, you'll need to add a seam allowance for each edge, then multiply the total height by 2, so you can cut out one long strip then cut it down length-wise so you'll have two matching strips ; one for each shoe. I folded over my seam allowances and ironed them flat, then sewed them on the machine for a neat finished edge. Then I tacked them and glued them on exactly the same as when attaching the linings to the the soles and when attaching the uppers to the soles. This final binding hides and secures everything and gives a really nice finish.

Step 8: Elasticating the Heel Only

I stayed wildly in love with my shoes for about 2 days before I decided to alter them. The fit was superb, but I didn't like the way the elastic went all the way around the top of the shoe, (they reminded me too much of swimming shoes, which is great to know if I ever want to make my own swimming shoes!) and I thought it might be good to show some alternative ways of finishing off the shoe, so here I show it with elastic only in the back of the shoe and in the next step I'll show how to add a strap across the instep.
Please bear in mind if I had intended from the beginning to only put elastic in the back I would have made the casing accordingly, now that casing is sitting empty, there could have been batting in there, all the way up to the edge of the shoe upper, it doesn't affect the fit of the shoe, it's more a styling point.
So first I took a stitch ripper and picked out the stitches that had closed the casing at the back of the shoe, then picked open the elastic itself and pulled it out. I wanted to replace it with a flat ribbon elastic, which happens to be a great deal easier to sew than the stuff I was taking out (wont need the thimble and pliers for this type of elastic). I wanted only the 5 inches around the back of the shoe to be elasticated. This type of elastic comfortably goes from 3 inches at rest to 5 inches when stretched, so I cut a 3 inch strip for each shoe.
I threaded the elastic into the casing, 2.5 inches in either direction plus the seam allowance for the back of the shoe, which in my case was 0.5cm on one side of each shoe, if you forget about that seam allowance your elastic will go in lopsided. I didn't need a safety pin because it was a short distance to push the elastic in and more importantly I would have had no way to take the safety pin back out. Once I had the elastic where I wanted it I held each end in place with a straight pin, then I sewed each end in place and also sewed the back of the casing shut again.
That's it, there's a couple of shots of how the shoe looks at this stage. I think it looks a lot less water-shoe-like than previously.

Step 9: From Too Plain to Mary-janes

Still felt the shoes were just too plain, so decided to show how to add a strap, I put elastic into the strap but there is no need to use elastic (anywhere in the shoe, if you don't want to) a simple strap on it's own will do a fine job of keeping the shoe from slipping off, however if your decide not to put elastic inside the strap you may need to attach a buckle or button to the body of the shoe so the strap can be tightened. Also bear in mind if you know from the beginning that you would like a strap on your shoe you can easily add one (or several) to your pattern pieces and that'll save you making it now. But if you decided to add one at the end, here's how I did it. First decide how long the strap needs to be, put the shoe on and measure across the foot at the point you intend on fitting the strap, add a seam allowance to either side (this is where you'll attach the strap to the shoe). Rather than making a strap from scratch I noticed that the hem from the shirt I had cut up to make the shoes was just slightly larger than the elastic I had used for the back of the shoe, so I used that to make a strap I worked a row of tiny zigzag stitching around the cut edges to keep it from unraveling. You could just as easily make a strap by measuring the width you would like the strap to be then multiply that by 2 and add a seam allowance for each side, then measure the length needed and add a seam allowance either end (this is where you'll attach the strap to the shoe) then, reverse sides facing out, sew up the length and one of the short ends, flip the strap rite sides out (via the one remaining open short end) top stitch of desired, then proceed as I did with my short-cut strap. I wanted my finished strap to be just under 3.5 inches long, after I allowed 5/8th of an inch on either side to attach the strap to the shoe the total length was about 4.75in, I made one for each shoe. I wanted the elastic to stretch comfortably to about 4 inches so I cut two pieces (one for each shoe) that measured about 2.5 inches at rest. Then I threaded the elastics into the straps and tacked in place with pins, and then sewed the elastic into place. I then tacked the straps onto the shoes using pins, and finally sewed the straps onto the shoes.

Step 10: Finished

These last images show the finished shoe in natural light and how 4/5 days of wear becomes apparent on this type of sole binding, some other material would be more suitable and long wearing, but I really wasn't concerned about such things when making these prototypes. I did this to see if I could and to learn, I hadn't really thought I'd end up with something I would want to wear, but they are amazingly comfortable.
Also pictured are a cheap pair of imitation ugg style boots, I had previously cut off the top several inches then folded over and sewn down the exposed lining to make more of an ankle high pair of ugly booties. I took these apart for the soles. After I tore off the uppers there was something stuck to the inside of the soles that was exactly like cardboard, I picked it all off, later I soaked the soles in some warm water to loosen the glue and scraped off the remaining gunk. I plan on using these soles for the next shoes I make, I'll probably cut out a piece of thin rubber, like from a yoga mat, or maybe a piece of lino, to replace the cardboard that was there, but I guess cardboard would work too, and then I'll treat them as I did the flip-flop soles.
That's all folks! Anybody who actually reads this far deserves some kind of tribute, let me know in comments what that should be.
If anyone has got any queries I will do my best to answer you in comments, and if anyone has a go at making their own shoes following reading this, (or otherwise) I would be delighted if you would post a pic of your work.