Pinball machines may seem like a good Maker project, but the mechanical components are quite involved. “Joesinstructables,” however, decided to take on this project on using an Erector Set, solenoids, and an Arduino board. In order to get around the challenge of using a heavy steel ball, he instead used a much lighter ping pong ball, sensed in the game by laser tripwires.
A number of solenoids propel the ball around and sound a service desk bell whenever a target is hit–one to three times depending on the difficulty level. Once the ball comes to rest in a target, a laser tripwire automatically triggers a solenoid to eject the ball, putting it back in play.
You can see more info on this build here, or even check out an earlier version for more inspiration!