This 3D printed puzzle is one of my most complex and lovely designs.
It takes thirteen steps before the first piece comes free. The 'switch' is flicked at step 5. When reassembling the puzzle, it may be easier to slide the switch piece with a pair of tweezers or a small pointy thing. One of the steps in the solution is a rotation, which makes it harder for computer programs like Burr Tools to find the solution.
This 5 cm hollow version has been optimised to provide maximum puzzle size at minimum cost. It is also ideally suited to being dyed in a variety of colours.