Fidget Hinge

I would recommend the L3 because it is a good size to swing back and forth without it hitting your hand.

This is a toy that you can bend very easily in one axis. If you swing it back and forth quickly, it makes a nice clicking sound. After you print it, the toy will be stiff, and you have to snap it, so it can start moving.

The L_ represents the amount of hinges it has. L1 would be the smallest, and L7 would be the biggest.