A box that looks impossible to open but is actually easy (when you know how).  There are 2 versions included, one is solid and the other has a secret compartment.  Print one or both.

This is based on an old engineering design that was originally made from Brass and Steel but redesigned for 3d printing.  Made entirely using Bambu Studio.

The design of the slides required some trigonometry to get the angles correct so that they look correct when assembled and placement of the various elements has to be perfect in order for it all to work.