This is one of my favorite mechanical puzzles in the category of recreational topology. It is easy to make using wooden materials. For the curious minds, here is a 3D version. Once the two parts-- the board/stick and the bead-- are printed. Please use a piece of string (rope, yarn) to assemble it as illustrated. The challenge is to move the bead from the left to the right or vice versa. The main idea is to move the knot back and forth through the middle opening. Let's me not spoil the fun of the puzzle here.

Reference:

Gardner, Martin, 2008. Origami, Eleusis, and the Soma Cube. Cambridge University Press.