Iris box

A very cool 3D design I found on Thingiverse. It’s printed pre-assembled, meaning all the pieces are printed in place and the box can be opened and closed by twisting:. First you have to force it a bit, but once you manage to get the blades free, it gets smoother every time you open and close it. The left box is as it comes out of the 3D printer; the right is in its (nearly) closed position.