How much do you think a potato cannon can run for? It's simply made with PVC pipes, a 2', 4' diameter combustion chamber, with a 4', 2' diameter barrel? It's a really fun toy, but can be a little dangerous. I launch potatoes, lemons, and even golf balls out of it. (To launch a golf ball, I simply pack a wad of newspaper tight into it and put the golf ball in it after.)
