FINAL

I layered up the bottom piece for more strength & support! It also appears better visually this way.

The final weighs 1.6 kg and has absolutely no glue holding it together. This it can be disassembled into a flat pack at any moment. 

MORE TESTING

This is roughly my third full-size prototype, trying to maximize the triangle to triangle effect. However I feel as though I am loosing ridgidity as I am increasing the visual effect. My final will still have the visual effect, but a second layer of xanita board in the weak points to keep structural properties yet not loose the visual effects.

The flat-pack design made it possible to lay out two stools on one sheet of xanita board, 

which comes in a sheet that is rough;y 4ft x 8ft. 

Below are the dimensions for the flat-pack design. 

The drawing & descriptionsn below should help to understand how the flat-pack is constructed into a 3D stool. 

PROTOTYPE 2

Xanita Board can not be laser cut as the laser cutter gets lost inside the corrugation.
However the router can be used to cut out and even etch/route the xanita board surface.

The design has curves in the top and bottom to create a more clean and elegant look.  The top piece slots into the bottom piece. Which creates the issue of how the bottom piece connects to the seat-top. I will create another prototype where the seat-top is partially routed so that the bottom piece can sit in it, which makes for more stability.

XANITA

My initial hope was to build my stool out of cardboard. However, the standard thicknesses of 3 mm did not satisfy my need for rigidity and flexibility. I wanted to be able to curve edges without loosing all the structural properties. Xanita board is made from composite fibre boards mostly from recovered and up cycled cellulose fibre waste from cardboard and bagasse. It remains lightweight yet hast much more structural properties than regular cardboard. Judging by the weight of the material, the entire project should result in a weight of less than 1 kg, which is quite incredible.