Plenulum

Each of these forms consists of four cubes. They are called Tetrominos. One can build a right parallelepiped from them.

Each time a ball goes through the switch changes itself over. Therefore it only occurs rarely that a ball passes all switches.

Because a ball becomes faster when scrolling down, the intervals between the tones are closing in.

In the corner mirror the ball appears to run in the opposite direction.

Only if a jack is full it continues. Three balls fit into the first jack, two into the second.

If you turn the screw with the crank the ball is raised.