We were inspired by a post on Twitter by Olivier Longuet shown below.
The object in the photo is an icosahedron, a 20-sided 3D shape, made out of three golden rectangles with side lengths that obey the golden ratio (1:1.618033…).
To make a cardboard version of the icosahedron, print out this document and follow the instructions!
You can also make this out of wood or other materials that can be laser cut. Our files including cardboard template and more directions are here if you want a pdf, svg, Corel, or AI file. If you make the frame for wood be sure to make the center channel the same thickness (or just over) as your board. Proportions are always 1: 1.618 short side to long side and the slot is going to be 1.618 – .5 in length. Have fun!