A simple yet deceptive puzzle box.
Note: You will need some non 3D printed items to complete the box and make it functional.
-two 2mm X 10mm strong magnets
-one 10mm metal ball bearing
A slightly smaller magnet size is ok as long as it's no thicker than 2mm and strong enough to hold the ball bearing in place in any orientation.
Glue the repulsive ends of the magnets, one inside the bottom of the round hole of each half. You will place the ball bearing into the deeper hole, slide the two halves together, then give the side the ball bearing is on a nice hard smack to make it jump to the magnet on the opposite side. At that point, the ball bearing will lock the puzzle box in place and keep it from being opened. To re-open, simply smack the opposite end to make the ball jump again. The puzzle is in that those who try to solve it won't know about this internal mechanism and will assume it's impossibly joined by the dove tails instead.
There is a secret storage/prize compartment inside of the puzzle box when opened.
Dimensions: 102mm x 70mm x 102mm (in total for both halves together)
Bonus: I've included 2 versions. A plain simple smooth version, and a very heavily ornate version. I'm not sure how easy the ornate version will be to print, but I've included it anyways.