Homemade 25mm Sniper Cannon
These kids have overprotective mothers that won't let them play with real guns, so they decided to build their own out of PVC. The gun "boasts a two-and-a-half-foot barrel that is one inch in diameter, has custom bolt-action mechanism, a modded sprinkler valve as the primary firing valve, and a $40 sniper scope." There is an instructables online if you want to make your own, but I suggest you don't, because that would make you a dork, like them (and these guys). Potato guns are fine though, because I made one. There's a video after the jump, featuring the gun shooting a CO2 canister THROUGH a cardboard box! All the way! It goes ALL THE WAY THROUGH. That's power. Wow. I mean, wow. I think I felt a little movement in my pants. Wait, no, cat crawling up my leg.
Video after the jump.