Dodecathing
We were asked, by maths YouTuber Matt Parker, to build a support for a 1m diameter solid shape that was to be built in a workshop session in the Big Feastival in the Cotswolds and used as a giant mirror ball.
The structure ended up as dodecahedron, inside an icosahedron, inside the final shape, which was mathematically satisfying, even if noone ended up seeing the inside. It was made of 3D printed, CNCed plastic and aluminium parts.