This puzzle you can either 3D print or make using some M16 & M8 Brass nuts and bolts.
The origional idea for this puzzle is based on a puzzle from "homemade puzzles" http://homepage.ntlworld.com/bruce.viney/Bolt%20P...
How it works
The aim is to get the washer off the bolt. The idea is the magnet is glued into the top section of the main bolt with epoxy. Which will hold the steel rod in place when the assembly is together. To open the puzzle you need to slam the base on a hard surface dislodging the rod and allowing you to remove the other parts of the puzzle so you can remove the washer.