FoldForm — a Backrest for Your Stool

FoldForm is an add-on backrest and arm support for round top stools. Laser cut from a single sheet of metal, it folds by hand into form along pre-cut bend lines and clamps onto any stable flat-topped surface — converting it into a chair. Minimal tools, minimal skill, maximum payoff.

FoldForm comes out of a very specific context. Design students at an institution — temporary occupants for about five years, not allowed to make permanent changes to their surroundings. Doing diverse kinds of work, needing their space to adapt with them — but the college has stools, not chairs. Rather than buying something new, FoldForm is the answer to that gap. Cut the sheet, bend it by hand, clamp it on. That's it.

It's part of Project Patch — a design project about building support objects for temporary spaces, working with what's already there rather than replacing it.

Hardware

1. 1.5mm Galvanised Iron sheet
2. 2mm steel wire / cable — approx 1 meter per unit
3. Turnbuckle
4. Makki (screw eye)
5. Rivets — 10 per unit

Tooling

1. Access to a metal laser cutting service
2. Angle grinder with buffing wheel / hand files
3. Sandpaper
4. Rivet gun
5. Screwdriver
6. Hammer or plier
7. Flat surface and table edge for bending

Optional

1. Spray paint
2. Buffing compound for finishing

Available in CEPT workshops

1. Angle grinder with buffing wheel
2. Rivet gun
3. Hand files

Download the attached DXF file and take it to your nearest metal laser cutting facility. Use 1.5mm Galvanised Iron (GI) sheet. Standard sheet size is 4x8 feet — one FoldForm fits in 2.5x4 feet, so try cutting multiple units from one sheet to bring the cost per unit down.

The template has two parts — the larger piece forms the back and arms, the smaller one forms the seat bracket. The pill shaped cutouts are your bend lines and the 5mm holes are for riveting during assembly. The cut outs should look like this.

Note — a PDF preview is included for reference only, at 1:1.5 scale. Do not use it for laser cutting. Always use the DXF file.

Take an angle grinder with a flap disk attachment hold it at a 45 degree angle to the sheet metal and then run it along the edges of the sheet in clean long sweeps. Doing this once or twice on a edge should make a working chamfer take the burr away. Next use a Buffing sponge disk to round out the chamfer a bit and make a easy filleted edge. There after, This step is a bit time taking but goes a long way in making sure that the chair feels nice to use.

Follow the sequence shown in the drawings. Everything is designed to be hand bent — no special tools needed, just a table edge as a guide.

Bend the seat piece first, then the backrest. At the end you should have two shaped parts as shown.

Two tabs need special attention — the tabs at the bottom of the backrest are bent after the seat and backrest are attached to each other, and the front tab of the backrest is bent while the piece is sitting on the stool seat. Don't bend these early.

Place the backrest onto the seat and pass the tabs through the slots. Once through, bend the tabs down to lock the two parts together. At this point the chair is fairly usable — but nothing is fixed permanently yet. Then bend the armrests inward to your preference so they support your natural resting position.

This is the first permanent fixing step. Once done, the FoldForm can no longer be flattened back into a sheet.

Start with the rivets. Pass rivets through the holes near the base of the backrest and seat and rivet them in. 10 rivets total — 5 on each side.

Next, the wire and turnbuckle. Take about a meter of steel wire. Pass one end through one side of the wire stopper, loop it through a hole in the seat, pass it back through the other side of the wire stopper, and hammer it shut to lock the wire in place.

Take the loose end of the wire and thread it through the two loops on the other side. Loosen the turnbuckle to its most open setting, pass it through and measure the length, then make a loop and pass it through the turnbuckle. It should feel relatively snug at this point.

Now tighten the turnbuckle toward its closed setting — the whole seat assembly will begin to tighten and pull together.

Congratulations on your own custom made backrest. If you want to make it more yours — add etching, patterns, or cutouts directly into the laser cut file before cutting. The file is yours to modify. Now put it on a stool and sit back. Or don't stop there — try FoldForm on other flat topped surfaces and see what happens. A bucket, a crate, a stack of books. If it's stable and flat on top, FoldForm will probably have something to say about it. Use, don't abuse, enjoy. The seat has cutouts to let flat straps pass through, and additional points can always be drilled and modified to suit your needs. Experiment, play, share, collaborate. Thank you for going through this — enjoy.