Marble Machine 8x6x5" No.6
The helical lift is in the center. It raises the balls on its two sides. These two tracks go into two switches which distribute the balls evenly into four track components like loop, vertical spiral, horizontal spiral and a twisty track between them.
Electrical components are engraved at the bottom. The speed is adjustable.
Full size with acrylic cover box: 200x160x130 mm. It has 10 mm steel balls.