The initial idea for the machine is that the parts aren't left behind. In this machine, 2 different marbles interact with different parts of the machine, but both end up together in the cup.

The first marble sets the second marble in motion by hitting the hinge, then falling into the cup. The second marble rolls down a slope, then starts the domino chain. The marble rolls backwards onto another slope and comes to a stop. The domino chain pushes a hammer, which swings around and hits the marble at the bottom of the slope. The marble then is launched into the air and lands in the cup next to the first marble.