The project that really took center stage was his ping-pong ball gun. You can think of this as a variation on a potato cannon, however his is built to run on compressed air, and it runs on much tighter tolerances. It runs off of a compressed air line and a standard wall outlet. After firing a few “dry” rounds, he proceeded to shoot off a few (ok a LOT) of ping pong balls filled with water. These things might not weight a lot, but they are moving FAST. A sheet of drywall was no match for them, and even particle board failed spectacularly when faced by a 1″ sphere of water.