[NightHawkInLight] a.k.a. [Ben] recently built an awesome high power air cannon out of PVC pipe. PVC air cannons ... Instead of using a ball valve or other such contrivance to dump air directly ...
A cheer erupts from the Hanover student section. Moments later those cheers turn to groans as one red ball knocks the green ...
The build uses PVC pipes for both the barrel and the air tank ... and firing is achieved via a ball valve. Of course, if you build such an air cannon yourself, just be careful with your aim.