While learning the basics of CNC machining so I could make microfluidic nozzles for my grad school research, I discovered objects known as turner's cubes: a cube within a cube within a cube. Legend has it they're given to apprentice machinists, who have to figure out how to turn one from scratch on a lathe.
I wondered whether I could do the same with another platonic solid, a tetrahedron, on the 3-axis mill we had in the lab. It was possible, though it turned out to be an exercise in workholding.
