For my very first instructable I'd like to share a project that I first did within a workshop several years ago.

Paper is a great material to work with and there are tons of ways to create awesome things utilizing it's properties. One of which is the skeleton & skin construction technique. Using this technique you can create sculptures, objects and even usable furniture like chairs!
It basically is paper mache, just like the ballon lampshades you might have done in primary school. Only a little refined. A frame made from studs (i.e. wooden bars) is covered in glued paper strips. Because paper has the charecteristic of expanding when wet, the strips will tense as they are drying. They become smooth and leathery when dry. So you end up having a structure made from bars withstanding pressure and a skin that is able to take great tension. Given that there are several layers of paper applied: So this will take some time! (depending on what paper you use, but we will get to that)

The upside is, you'll have a new piece of furniture that looks great and you can actually sit on.
Plus you can design it specifically for your ergonomic needs.

I am not a native speaker so I hope the descriptions are understandable and corrections are welcome.
Also most of the dimensions are metric but should be easy to convert.

Happy Making!

Step 1: Materials & Tools

Materials:

Paper (at least 80g / m2)
You will need about 4-5 m2 but this depends on the thickness of the choosen paper, we'll get to that topic in step 14
Lumber in either the dimensions and length according to the parts list or depending on your own design
Dowel stick, 8mm in diameter (cut to pieces according to parts list)
Wood screws 4x35 mm
Wallpaper glue (one pack of 200g should be sufficient)
Wood stain/dye if you wish to color the wooden parts
Hard wax oil
Wood glue

Although the paper itself is going to bear the whole bodyweight, it's obviously not the only material used. Therefore you need to have basic woodworking tools
Try Square & Protractor
Handsaw
Powerdrill
8mm Drill & 3mm Drill
Screw bit
Chisel & Handplane (not a must!)
Sanding Paper
Brush
Screw clamps (4 pcs)
Pencil
folding rule

Step 2: Draft Your Design

Before getting your hands on the tools and start making, you need to get an idea of what you're going to make and the best way to make it!
So I got into the habit of developing projects using CAD, but that's no must. Paper and pencil work fine to create your design and make the parts list that will ease the building process once in the workshop.

Although you can of course use the parts list to build the exact same chair as built in this instructable, i recommend to rather draft a design for a chair by your own. There's three reasons to that:

I used lumber in rather unusual dimensions (27x27mm) that i had left over from another project.
So you'd either have to size cut lumber to those dimensions, or change dimensions in the parts list for relevant parts.
Because I built two chairs of this kind before, I aimed for a pretty light design. The result are very slight angles (2°) on most of the parts which can probably be ignored after all. But if you decide to cut all angles in those positions required, it's going to be a lot of slight-angle-sawing...
The best reason is though, that drafting your on design means going the extra mile to make this project 100% yours. There isn't much that comes close to be as rewarding as something that you created from scratch. Plus the aesthetics of your new piece of furniture is totally up to you!

Building a chair is quite a challenge though, so I will update this instructable with a parts list for another chair that will be easier to build (easier angles for sawing & less parts in total) and use lumber in dimensions one is able to find at home depot.

Step 3: Start Preparing the Wooden Parts

Before getting to the fun (messy paper mache) part, we need to start 'prepping' the lumber. Means cut to size, drill, mitre, chamfer, sand and (most importendly) label all the wooden bits as shown on the parts list. How you work of the items on the list depends on what works best for you. I like working my way down top to bottom doing one step at a time and having all parts ready, before proceeding with the next step (i.e. size cut all parts from A to H, then chamfer and sand all parts in that order, ...).
Make sure to check off ready items on the list, to avoid double-work ;)

I used Pinewood for this chair but basically any wood is fine. With a hardwood like oak or walnut, even lighter dimensions are imaginable!

Step 4: Cutting to Length

The parts list is our guide for all the woodwork, so make sure you have it at hand. If you built your own design: even better because chances are less you will get confused over it.
Starting with the part A, measure the length required with your folding rule then mark the cutting angle (2°) with the protractor. This will be the 'guideline' for the saw. Turn the bar 90 degrees and mark a right angle to the lenght of the wood, meeting the line of the cutting angle. Using your handsaw, start cutting along the right angle on top as first orientation, then follow the angled guideline along the side of the bar. Before putting the cut part aside measure and mark the position for the dowel hole.

When both ends of the part needs to be cut at an angle, it is helpful to move the first mark a bit in from the end of the bar, otherwise you'd have to start sawing right on the edge of the wood!
Also, avoid branches. Those are weak spots to the lumber and are hard to work with! Start measuring for the parts left and right of the branch, that way it stays out of the wood you're going to use.

Step 5: Dowel Holes

It is no crime using screws to put the parts together. This particular design demands a rather late assembly and wouldn't allow all screws to be hidden though, so I decided to use self cut dowels and glue only.

Before drilling the dowel holes in the marked positions, protect the wood from chipping by taping around the bar.
If you are using a handheld Powerdrill, try switching the position of your head from front to side while watching the drill to make sure it sinks straight. Using a drill press obviously is the safest way though.

Step 6: The Surface

I cut chamfers on all edges of the parts using a handplane. Sharp edges are prone to chip off and should be avoided therefore. Also the lumber required at least a bit of sanding.

Step 7: The Cross

The cross will sit about halfway from the floor to the seat and helps stiffen out the legs of the finished chair.
In this step we'll take a look at how to use a chisel to cut the middle joint for the cross.

Mark the lines where the counterpart will go as stated on the parts list. Use your try square to draw them halfway down the side of the bar. That way you can easily guide your cut and will know how deep to go. Filling the part that is cut out with your pencil also helps to not get confused over where to cut. Once you've made both cuts you can use your chisel as a lever, going into one cut and pushing towards the other (instead of a chisel it is possible to use a carving- or even cutter-knife). Always work away from your body!

When you have a clean notch halfway through the bar, you can mark the center for drilling a dowel hole as shown in the picture. Do a try fit when you have both parts ready to see if they fit.

To control the depth of the dowel holes at the ends of the bars, wrap your drill bit with tape at 1.5 cm. Doing so also at the counterparts (chairlegs) will ensure to be at 3 cm depth in total so the cut dowels will fit properly.

Step 8: The Front Legs

Now the legs of the chair are a bit tricky, as each one is different to the other. The rear legs will later hold the backrest, so there are different from the front ones already. Because there are those tiny angles and the cross, that will partly fit inside the legs you cannot do the same leg twice and just turn it around, you have to mirror it!
So there will be a front left and a front right leg that you should label that way at the bottom, once you've finished it.

Start by measuring the joint for the cross on the inside edge of the leg as shown on the parts list. Use your saw to cut along the right angled lines starting right on the edge, and going down to the end of the filled area. Again use you chisel to clear in between the cuts to get a joint as shown in the picture. Drill the dowel hole in the middle of that joint. Use tape (Step 7) to get the depth right.

Mark the angles at the top of the leg and then saw along the lines to get a proper fit with the seat when assembled later. As the angle is 2° only you can also sand it down if cutting is too fiddly. The easiest way is using a plate sander if you happen to have one.

Step 9: The Rear Legs

On the rear legs, you will have to do the same joints for the cross and also you'll need to drill dowel holes in the upper part of the leg according to parts list. The joints for the seat have a minor difference to those on the front legs: As the rear legs continue past the top of the seat, the joint for the upper bar of the seat frame will start right above the other one.

Step 10: The Dowels

In this step we only cut pieces from an 8mm dowel rod to the length of the needed dowels according to our parts list. To prevent the round rod from rolling about, it's best to rest it on a V-Block when cutting. ...Or have a firm grip! ;)

Step 11: Wooden Parts

So that's it for the wooden parts, now we can start the fun!

Step 12: One More Thing...

...Actually I decided to use wood stain to darken that light pine wood and make for a stronger contrast to the paper. I had stain in dark gray left over that i brushed the legs and the cross parts entirely with. For the frame parts i only needed to dye the tips...

Step 13: The Frame (Skeleton)

Still no sticky paper-hands because we need to make those frames at first, that the paper goes onto.

The seat will be made from the parts A & B and you need to start by measuring 27mm (thickness of the bars) in from each end of each bar to define their position. With those marks made, you can place the frame in front of you, the longer B parts on top of the A parts (that way the screws used will be on the bottom side when turned around and won't be visible). Then drill 3mm holes through the upper bars and put some glue on the lower ones where they cross. Now fix each crossing with a 4 x 35 mm screw and check the corner with a try square.

The frame for the backrest is made almost the same way (parts C,D, G) only that there's that 2° angle on both sides, so each part has their specific place, when assembled it looks like on the picture.

Step 14: The Paper (Skin)

Now we finally are ready to mess around with paper and glue!

The picture shows a variety of paper i had lying about, but i ended up using one particular wallpaper mainly. That is because wallpaper is very thick and therefore already pretty sturdy. The benefit is that you'll need less layers with that kind of paper, the downside that it is harder to work with because it's stiffer and soaks slower.
Using an 80-100 g/m2 paper you will need about 5-6 layers that need to dry in between each layer (drying takes 1 day). Newspaper is not suitable because it's too thin and will tear easily when wet. You can try to do a last coating in newspaper, when you can work on the previous layer, but there's no way to start your first layer with newspaper or similar thin paper.
I found that brown packaging paper works pretty good and has a nice look because of that leather-like color.
But the choice of paper is up to you, you will get to know the material better with each layer!

Step 15: Prepare

Stir the wallpaper glue into cold water in a ratio as required on the bag (maybe a bit more water, you really want the paper to be soaked!) then leave to swell while preparing the paper.
If your paper comes on a roll (like wallpaper does) tear a sheet that's a little wider than the width of the seat (~60 cm). Then start tearing strips lengthwise along the sheet, between 1/2 -1 1/2 inch wide.
You will figure out that paper always tears better in one direction than the other. To tear the paper in evenly strips you need to follow that direction. It's also better to tear some more strips than what you expect to need, that way you won't have to start tearing when in the glueing process.

Step 16: The First Skin

Use some sort of base/underlay when soaking your paperstrips. Anything thats coated and doesn't soak up the glue or sticks to the paper. I used a scrap board of coated cabinet inlay, but anything like a cutting mat or similar will work. The wallpaper glue peels of easily once dried.
Start by coating the board with glue using a big brush. That way you make sure the paper sticks to it and doesn't curl up, also it helps soaking the paper from both sides.
Next lay your paper on, one strip close to another. Now brush your paper strips with glue on top.

It takes some time for the paper to soak properly, depending on the thickness of the paper used. with wallpaper you'll have to let it soak for at least 3 minutes, but you'll get a feeling for how wet the paperstrips need to be to stick together and to the wood properly. (You can glue-brush the wooden frame as well to help the paperstrips stick to it, but usually there's ne need to do so.)

Now take the first strip and wrap one end around one side of the frame, then stretch it lightly across the frame and wrap around the other end. Depending on the type of paper used you can stretch more or less before it breaks, but there's really no need to get to much tension on as this comes naturally when the paper dries.
Also be careful not 'push' the paper in a certain direction. The end wrapped around the frame will determine the direction the strip goes across the frame. follow that direction, don't force it in another one, otherwise there will be wrinkles! Once the frame is covered you dont have to start with the end of the strip but will be able to place it on top in the required direction and then work your ends around the edges of the frame.

When placing the next strip, do it in a direction that's preferably perpendicular to the first one. You always have to work criss crossing the strips across the frame. When the paper is drying, each strip builds up tension in the direction it is facing, so for a smooth surface the layer needs to dry with evenly applied tension in each direction.

Step 17: Criss Crossing

When working with curves as with this chair, criss crossing is crucial for another reason too:

The wood frame basically defines two planes on different levels. By stretching paper strips between the wooden bars we connect those two planes to create 3dimensional curves. Criss crossing will ensure that one paper strip is not going to make a straight line between it's two ends when drying and building tension, but is hold down by another on top of it and so on and forth.

Step 18: Light Test

Hold your covered frame against the light to see where there's still gaps or thinner areas within the layer.

Step 19: One Day Later

The next day your first layer has dried and is ready for the next 'coating'.
I covered the backrest in the same way as the seat frame.

Step 20: Second Layer

The colorful wallpaper was an attempt of mine to see how I'd like it and if it might be suitable as top layer. I was just about to decide that it was a little too edgy for my taste and that I'd rather go for a 'cleaner' finish when my partner came in and decided that it was going to be her chair and she really liked the edgy wallpaper!

Nonetheless, at this point I started the second layer with a thinner paper (100g) that soaked much quicker and was a little easier to work with. It helps a lot to make for an even surface as well -> Wallpaper is so thick that there's quite a difference between 3 strips (less thick) or 5 strips (way thick) layered on top of each other. You have to be very careful not to end up with a bumpy surface. with thinner paper you can even out a lot better!

Brushing glue on the whole of the first layer helps to start the second one. The printed, dry surface of the wallpaper wouldn't soak much glue from the fresh paper strips so by brushing it with glue beforehand you ensure a wet in wet bonding that is much stronger.

Step 21: Third (last) Layer

How many layers you will need for the seat to be viable really depends on what paper you're using!
Usually it takes about 5-6 layers for such a chair to be able to sit on, but thats with a paper of 80g-100g /m2.
With wallpaper the seat appeared to be very strong after the first layer already, so with another layer on top already, I decided the third layer would also be the last one already!
Of course in that edgy wallpaper again because the customer asked for it! ;)

Note: The backrest requires even less material becuase the force working on it is less than that one on the seat.
I therefore did only 2 layers of wallpaper on the backrest.

Step 22: Dry Fit

On projects like this I always do a dry fit before the parts come together with glue and clamps. This way I ensure everything fits in its position properly. This one looks fine to me so let's start glueing!

Step 23: Fixing the Front Legs to the Seat Frame

For this step we obvious need wood glue, four of the size 1 cut dowels, 4 screw clamps and some scrapwood blocks to protect the legs from clamp marks. A hammer or wooden block to drive in the dowels also helps.

Start by glueing the dowel holes (both on the seat and the ones on the leg) and spots on the seat were the leg will go. Insert one dowel in the lower bar of the seat frame. Put the leg on and press in place, then insert the next dowel through the leg and seat frame. Now clamp both directions as shown in the picture. Proceed with the other leg the same way.

Step 24: Glueing the Cross

Take both parts of the cross and apply glue in the joint were they will fit one in the other. Also glue the dowel holes of both parts. Slot them together and press the size 3 cut dowel in, using a hammer (with a wooden block between workpiece and hammer for protection) or a clamp.

Step 25: Position the Cross

Glue the size 2 cut dowels in the joints of the front leg and apply glue on both, the joint and outer part of the dowel. Fit the cross into the joints and proceed with glueing the rear legs.

Step 26: Fixing the Rear Legs in Place

Start by applying glue to the cross joint and seat frame as shown in the pictures. Get the leg in place and lock it onto the cross before positioning at the seat frame. Lock in place with size 1 cut dowels and clamp as with the front legs in step 23.
Once the rear legs are clamped in place and the cross sits properly, you can apply pressure on the cross joints by using a frame spanning tool, a strap tensioner, rubber straps or even a strong tape that you wrap around and stick to itself.

Step 27: Placing the Backrest

After the glue on the legs has hardened we can proceed with the last step, glueing the backrest!
Apply glue to all dowel holes in frame and legs. Press the size 4 cut dowels through the lower holes of the legs and in the frame of the backrest.
Because the rear legs come in a fair bit at the top, we won't glue them right to the frame of the backrest. Rather aim for a gap of about 1/2 inch, that way the backrest sits slightly backwards and makes for a much more comfortable sitting position. Use the size 5 cut dowels and glue them in as in the picture.

Done!

Step 28: Try to Stand on It!

...Or maybe just take a seat and rest for a moment, enjoying your new piece of furniture :)

Step 29: Variations

Those are the two predecessors I'd like to show as inspiration and possible ways of what a chair in the skeleton & skin method of construction can look like. The armchair is very similar to the chair built in this instructable in terms of how its made. The seat and backrest were made unattached and then screwed to the leg/armrest frames.
The other chair is made using strings to create those real wide curves. It is an example of building the entire skeleton first and then 'bandage' the whole thing opposing to built a chair kit and fix everything in the end.

Now I am curios to see your Paper Chair designs!