Update: Figured out how to export the files in the proper size and orientation from Inventor. Changed the fillet to a chamfer at the bed side of the box for a better print.
A double dovetail optical illusion box with a magnetic internal pin system to keep people puzzled about how it was created. There's also a secret compartment inside for hiding small things. In order to release the pin inside, give the bottom of the box a good smack on a hard surface until the bottom pin falls off of the magnet in the upper box into the recess below.
you need some 8mm magnets that I found at dollar tree (most craft stores have them) to glue into the top box recess, and then glue the top pin over top of the magnet so that the bottom pin doesn't magnetize too strongly to fall down. you'll also need a M4x16mm screw to thread into the bottom pin part to create a magnetizable pin (the head of the screw should be about 7.7mm).
Designed to print with a 50x50mm base, but more than likely will scale larger if you can figure out a different solution for the internal pin system (larger screw? Bigger magnet?). I find 3 or 4 outer shells works best for the box parts. Nothing requires support material. The only part that needs a brim is the bottom pin for better bed adhesion, print the bottom pin upright with the "pointed" side towards the bed. 100% part cooling fan.
If you get any boogering inside the pin recess in the lower box or on the pin itself it can mess up the tolerances and the pin may not move smoothly and could jam. it's generally a good idea to make sure the pin is clean and to use a drill bit to scour out the bottom recess by hand if the pin isn't freely moving in and out.
Based on a tutorial by TFI on Youtube https://youtu.be/kRLpPY6dn-0 and then a lot of iterative design to make the internal stash and figure out the tolerances on the internal pin system. Designed in Autodesk Inventor.