At my last job a buddy and I pieced together an awesome
potato cannon which provided for hours and hours of great fun. Other folks take vegetable projection much more seriously as you'll discover here at
siege-engine.com. The second cannon I made resides at my Mom's cabin in Atlantic City, WY and is a favorite with visiting grandkids. You quickly run out of potatoes in a remote town like AC, especially if you shoot them over the nearby hills. We've also used apples and one time I had a competition with the kids to see who could design the best projectile using paper, cardboard, and duct tape. My brother says that a tennis ball works but it's tough to shove down the tube...jeezum, not sure I'd try that.