Evil Mad Scientist Laboratories, the same demented tinkerers behind the Meggy Jr., constructed a tabletop, mechanical version of Pong out of plywoods, timing belt pulleys, microswitches to detect when the ball hits a paddle, pusher solenoids to kick back the ball, and an ATmega168 microcontroller that powers the paddles.

The result isn't perfect, but it's playable! The steel ball bearing needs a little more push to cross the field, and it sometimes curves instead of traveling in a straight line (a lot like the player-guided balls in Magnavox Odyssey's Tennis). I love the score wheel, though, and that you can direct the paddles with knobs.

Evil Mad Scientist Laboratories has posted photos and details on how it created the tabletop Pong setup, so if you want to build your own, you could probably figure out how with all that information. I've also embedded a video after the break of the machine in action: