This Riddle was formerly designed and build by my grandfather ...but of course not with a 3d printer. Instead of a additive manufacturing process he was working with a substractive process.
3d designing and printing this is soo simple.
WARNING: The riddle is really hard. Mostly all people need at least one hour to solve it!
If you are having a hard time sliding the parts into each other you might wanna use some sand paper and sand the edges until all parts move smoothly.