Mechanical puzzles are those with moveable, though constrained, objects ...

Logic Cube with Balls (Falling Marbles) is one of the most simple mechanical puzzles known. The puzzle is a transparent cube containing 26 balls. There is an empty space (the place of the missing ball), which makes it possible to roll the balls inside the cube.

4x4x4 Logic Cube is a far more daunting challenge than the 3x3x3 cube. The number of pieces is far greater, and there are no "fixed" pieces to serve as a reference.

These puzzles are a challenge for anyone!