Introduction: Rolltop Waterproof Backpack

About: human, does many things

how hard is it to make a backpack? it's just a big rectangle with some straps and some other pockets, right? But when you're looking for a backpack, it's somehow impossible to find a backpack which is fully waterproof, visible, easy to see, and just the size you want.

So here is a backpack I made, fully waterproof, for around $30. You can spend more on materials, or you can spend less! I thrifted all the nylon straps & buckles for the teal backpack--for $3 I found an old TV carrying case that had ~3 yards of 1.5 inch nylon, 2 triglides, and six buckles, and all it required was some seam ripping. For the floral backpacks, I spent even less--thrifted curtains were $2.50, belts $0.50 each (five belts per backpack).


- 1-2 yards of fabric for exterior of backpack (I found cordua for $5/yard on sale at my fabric store, but look at thrift stores for big trench coats, curtains--you want something with some pretty significant thickness and heft to it)
- about 3 yards of 1" nylon
-2 triglides to match your 1" nylon (if you use thicker nylon, use thicker triglides)
-2 buckles to match your 1" nylon

-1/2" thick foam (padding for the back & bottom)
-waterproof fabric for liner (I used tarps--$10 for a 10'x12' piece of fabric, but feel free to use shower curtains, laminated cotton, you name it. You can also use non-waterproof fabric if you don't want a waterproof backpack, and just like the look of a rolltop. Or you could do a different top! But then you probably want a different instructable.)
-seam sealer (and definitely use seam sealer. Don't just tape over your liner edges with duct tape. I am not endorsing that at all, as it would be cheap, functionally waterproof, and very low-budget for this backpack you spent a lot of effort making. Just kidding, I totally sealed the edges of the liner with duct tape, which is cheap & waterproof & totally fine to use in something that will not be touching your skin at all.)

-reflective fabric (I managed to snag some reflective vinyl from my mom, who had it lying around)
-1" thick foam, if you want to do padded straps, or if not, use heavier, 2" cotton webbing (also easy to thrift in form of belts)
-mesh fabric for side pocket

Step 1: Your Pattern

I've drawn out all the pattern pieces I used in the picture above. I highly, highly suggest you measure these pieces onto newspaper, pieces of plastic, or just printer paper taped together, because you'll use them multiple times.

Coming up with the pattern was the longest part of this process! Feel free to adjust your backpack accordingly--this backpack generously fits a 17" computer, and you may want to reduce the size if you plan on carrying less.

It's also important to get a good schema in your head of how this pattern works before you make it, so here it is: this is a rolltop backpack. Each of your pieces will be ~25" tall: 17" of that will be for the body of the backpack, and the remaining eight inches will roll down. The rolled top is fastened by the two buckles, as pictures, which are attached to the front of the bag and the back, just under where the straps come out.

When you make these backpacks, it's important that you do all the small details first. Plan your pockets. Plan where you want to add D-rings, to attach your keys, where you want to add reflective stripes, to be more visible on a bike at night, where you want an extra strap to attach a blinky light for a bike or if you want nylon on the sides that can cinch the backpack down. How many pockets do you want? Do you want pockets on the side? Do you want a water bottle pocket? Feel free to use exactly my pattern as seen here, but I also encourage you to branch out! You are just sewing a rectangle with some shoulder straps which rolls down at the top, and you should put whatever crazy things on it you want. Do you want to embroider flowers onto the front flap? Please send me pictures. Do you want to cover it with sequins or peacock feathers? Yes, again, I want you to do that so much! If you think having a backpack with elastic cords all over the front and sides would let you carry things with greatest flexibility, then sew that elastic on!

Step 2: Prep Materials

If you are buying new fabric, if you are using brand-new never-before-used nylon, great! You can skip this step.

Otherwise, welcome to my favorite step! Get comfy. This is the time consuming one.

The reason I wanted to make a backpack in the first place is because of this blue trench coat, pictured above. Yes, that one. I have had this trench coat for ten years now and I love it to pieces. Do I ever wear it, you ask? The answer is a resounding no. I saw this trench coat in Burlington Coat Factory when I was fourteen and fell in love with the color (a blue so intense it doesn't really even come across in this photo). The fact that it was a size 14 petite did not stop me from forcing my mother to spend the $30 to buy it for me. And while I am many things, I am not and never will be a size fourteen petite, so I can count on one hand the number of times I've worn this coat. (It's currently disassembled, seams picked apart, waiting to become a backpack.)

If you're making a backpack from a trenchcoat, great! Trenchcoats are often made of four or five yards of fabric and are usually made of more sturdy and weather-proof fabric great for backpack exteriors. However, you will spend a lot of time prepping. Get a seam ripper, and get familiar, because you will spend a lot of time ripping out all the seams in this trenchcoat, and tearing it into five or six pieces (two back pieces, two front pieces, two arms, and liner). The great part of using a trenchcoat is that there are so many really cool things you can add onto your final backpack--epaulets become useful compression straps on the sides! Former trench coat pockets can become secret pockets sewn into the side seams! There are so many buttons! And the lining makes a really cute lining for the backpack itself, if you don't want to have a fully waterproof lining like the rest of this instructable.

As for other thrifted fabrics, go crazy! Find some interesting curtains, or some normal curtains you think would look good as a backpack (see my green curtains with gold and crimson embroidered flowers, which became two beautiful backpacks). Use duvet covers, overcoats (tweed backpack, anyone?), wool suits (hella stylish wool backpack yes please), old leather jackets (but beware sewing leather unless you know your sewing machine can handle it). I love looking through coats and suits at thrift stores--two often-overlooked sections with a gold mine of fabric choices and often high quality, natural fibers. It's much easier than you think to find wool and silk and linen when you're looking through all the disregarded suits!

Don't forget to look for other materials at thrift stores, too. Buying new nylon runs anywhere from $1-$3 a yard; in contrast, ugly duffel bags with yards and yards of nylon are just $3 each at the goodwill. Look for big pieces of luggage that have lots of nylon, lots of buckles, lots of triglide adjusters. Bonus points if they're ripped and aren't useful anyway! I got all of my nylon and buckles from a weird piece of molded plastic which was designed to hold a boxy, 90's television. Goldmine. And don't be afraid to branch out--the floral backpacks don't use nylon webbing at all, but instead the straps themselves, the webbing holding straps to bag, and the webbing which holds the rolltop closed are all woven canvas belts, which are easy to find at every thrift store, come in a variety of widths and lengths, and each one comes with its own closing mechanism. Don't like plastic safety-vest style buckles? Find belts with stylish buckles and add some vintage charm to your backpack.

The beautiful thing about making backpack is that you can make backpacks out of whatever you want. Make chevron backpacks, make floral curtain backpacks, make teal backpacks, make pinstripe suit backpacks, make quilted down backpacks! I just wish I could restrain myself, because now I want to make backpacks out of every mildly interesting pattern I see at the thrift store.

Step 3: Assemble Front, Sides, Bottom, Straps

Assemble the exterior of your backpack. Cut out your front & back pieces, your bottom piece, your two side pieces. I found it helpful to mark out 17" on each of these pieces, which are 25" long-- that way you know which 17" are the body of your backpack, and you know that the rest of it is for the roll top. DO NOT SEW THEM TOGETHER YET.

Assemble the front! Cut out the pockets. My pattern includes two front pockets with flaps: feel free to change this up and make a backpack with one wide front pocket, with three layered pockets sewn on top of each other, with no pockets whatsoever and just elastic straps sewn to the front. After you have sewn on whatever pockets you like, sew two pieces of 4" long nylon with the female side of the buckle attached to the front piece (see photo for placement).

Assemble the sides! This mostly involves placing pockets wherever you want them. If you want pockets to span the entire width of your backpack, as mine do, don't bother attaching them now--you'll just sew them into the seams when you join the sides to the rest of the backpack.

Assemble the triangles! These are the triangular pieces that will be sewn into the seams between the sides & back, where you attach your nylon so that your straps will connect to your backpack. Cut four triangles of equal size, pin edges down, then insert your nylon webbing onto one of the short sides of the triangle. If this sounds confusing, look at the picture for details. This is how your straps attach to the bottom sides of your bag.

Assemble the bottom! The only thing I did here was cut out another square for the bottom from durable ripstop nylon, to add an extra layer of thickness to the most durable part. If your fabric is thin, you want to seriously consider adding some extra fabric to the bottom piece, because it's going to take the most weight. I also added 1/2" foam to the bottom piece, between my two layers, to give some protection for all the times I drop my backpack with my laptop inside.

Assemble the straps! You have many options here. For the teal backpack, I sewed two tubes, turned them inside out, then stuffed them with foam to make the backpack straps. For the floral backpacks, which were a little smaller, I just used 2" thick cotton webbing. Again, you can be as elaborate with the straps as you want--I chose on the teal backpack to add reflective material (since this will be a biking backpack for me, visibility is very important!), as well as a nylon strap where I could attach a blinking light at night. You can add elastic, D-rings to hook keys, or whatever else you want. The most important thing is your comfort!

Once your straps are made, you'll want to sew a triglide onto the end, as shown in the picture. This is where your nylon webbing will feed through, making for the adjustable straps that make a backpack a backpack.

Step 4: Assemble the Back

Assemble the back! This is the most complicated part. After all, they don't call it a "back" pack because the front is the most important....

First, you're going to want some padding on that back: take your 1/2" foam and pin it to the back, just inside your seam allowances, going up to 17" (the actual body of the backpack not counting the rolltop part). You're then going to quilt it down--I found this easier if I put a piece of scrap fabric (I used old tshirt) on the inside part. I just quilted it in a simple diamond shape, as you can see here, but you can be creative here if you want to.

Next for the back: assembling the strap and handle! As per the picture, you'll need a strap of thicker nylon (1.5" if you have it, but 1" works if you don't). This strap will be sewn down to the top of the back, just above the quilted portion (the bottom of this strap should touch the top of the quilted portion)--but don't sew it yet! Cut out 8" of nylon to form the handle for your backpack, and place this in the center of your back nylon strip. See picture for handle placement.

Next to the handle, pin into place your straps. Now, in the same layer as your straps, you're also going to pin the eight inches of your nylon webbing which is attached to the male buckles. So on one strip of nylon now, you should have two backpack straps, with a handle in between them, and coming out from the same place as the backpack straps are two pieces of nylon with male buckle ends, which will be the other end of your rolltop fastener. This sounds complicated, but just look at the pictures--you'll easily be able to see placement and understand why these things go here.

Sew the backpack straps, the nylon + male buckles, and the handle ends to the piece of nylon. Then pin that piece of nylon along the backpiece, lining up the bottom of the nylon piece with the top of the quilted portion. Sew it into place. This will be hard to sew, because you're sewing through tons of layers here! Especially hard to sew if you're using a not-very-powerful home sewing machine. Take it slowly, lift your pressor foot up over the bumps where the straps are, and don't be afraid to go back and forth several times over the same area. In fact, sew this nylon strap to your back in at least three or four places. This is one piece you do not want to come unsewn.

Look at your finished back piece in pride! Now you have a padded back with straps & you can carry it around by a cool handle! Rad. So rad. Good job, you.

Step 5: Backpack! Assemble!

So yeah! now you have all the pieces! Just sew them together!

There's no secret to this. Use a lot of pins. I personally sewed bottom & sides together first, then front & back to that piece, but there's no reason you couldn't sew front-bottom-back together then set in the sides. Just whatever floats your boat.

You'll also sew your triangles that hold the straps in here, too: pin them at the back at the bottom of the quilted portion as you sew the sides to the back. Your side pockets are caught in these seams too. Pin a lot and make sure you catch all the layers of fabric as you sew. It's okay and probably a good idea to go over these seams several times.

Go slowly. Use a lot of pins (like, dozens of pins). The corners will be tricky (I made them more U-shaped and reinforced them several times).

Beware: when you are done with this step, you will have a fully functional backpack. It will not, however, be lined. It's really tempting to stop here, as everything looks totally done. You COULD stop here if you wanted to...

But! Don't! Please sew a liner! Otherwise your computer & books & pencils & backpack things will poke holes in your exterior fabric & rip into your foam backing & also it will not be waterproof at all. Even if you are not interested in a waterproof backpack, the liner is where you will put all your internal pockets--your laptop pocket, your pencil pockets, whatever you want.

Step 6: Sew the Liner

So the liner's a little tricky. To sew. Hahahaha. So, sew. It's late, okay.

Easy version: Cut out the rectangles for the front, back, bottom, and sides. Assemble to form a cube open on the top, with seams facing outward. Insert cube into your exterior shell, fold the top over & sew liner into backpack. Voila! Your backpack is fully lined and ready to go!

Medium (waterproof) version: Same as above, only you're definitely using waterproof fabric (I chose tarp, which is light & stays dry, but pretty noisy and rustles a lot). When you're done sewing the rectangle, use seam-sealer to seam your edges on the outside (wrong side of your fabric)--either real seam-sealer or duct tape. (I'm from Kentucky, yall. Of course I have secret duct tape seams.)

Expert version: sew in pockets! Cut a 17" long piece & make a pocket over your back 25" long piece, an envelope sleeve for your laptop. Add some long thin pockets to the front piece for pencils. For expert hard version, add a zippered pocket (oooooooh). For expert super hard version, sew in laptop pockets, pencil pockets, etc, using waterproof fabric, then seal the outside edges so they stay waterproof. (Disclaimer: I made the medium waterproof version both times & never the expert version.)

All liners go in the same way--wrong side to wrong side (seams are on the outside of the bag as you look at it, meaning when you look inside the bag you'll see no seams sticking out). Fold over the top of your exterior and stitch to interior. Fold down top again (double fold hides rough edges), and stitch again.

NOW you have a backpack! Look at you! Dump all your stuff in there! I'm so proud of you. I'm proud of us. Have a martini. Go use your waterproof backpack in the rain, you crazy animal. You deserve it.

Step 7: Take Pictures of Your Awesome New Backpack & Share With Everyone

Here are my baby backpacks! The teal one is my first one ever, made with cordura I found on sale. Here I am with it visiting Portland OR, the rainiest, bikingist city. For comparison I put it up next to my boyfriend's North Street bag (they make rad bags, also--his is a convertible backpack to pannier, which I did not feel brave enough to tackle this time around). You can see they're about the same size, but I like the double straps across the top better. I also put a lot more reflective accents for extra safety.

The floral one was a birthday present for a friend!

Take a picture, you know you wanna, you made one and now you're so proud! I'm proud of you.