Polyhedron Kaleidoscope
Polyhedron Kaleidoscope
Not 100% sure this counts as a functional print, since I purchased acrylic mirrors for this and cut them down. What I 3d printed were the templates for cutting the mirrors and the shell for holding it all together in the right shape and protecting it so my niece can play with it without breaking it.
Mirror templates: https://imgur.com/gallery/gKkYyYE
Images through the kaleidoscope, along with an external view of it: https://imgur.com/gallery/P4atHey
Templates, stencils, jigs and fixtures are absolutely functional printing. One of the best functional use cases of a 3D Printer is the abundant use cases of how it enhances another hobby. Just making a drill template so the holes are in an accurate layout is extremely helpful.