Free the star from the cage and put it back!
This brass puzzle was first introduced to me by Prague's own, Professor Bakalar. I borrowed it in Atlanta and returned it to him in Luxembourg half a year later. While in my possession, I managed to replicate it, with full permission, of course.
This Cast Puzzle version may be even better than the original.
It definitely remains one of the more amusing puzzles.
The key idea with this one is its "cage."