This looked a little too cool to pass up. Shoots a .30cal (5/16") stainless steel slingshot ammo ball (which is easy to buy in bulk). Runs on black powder, Pyrodex, Triple 7 or they even mention using the powder from fireworks. At $39, I may have to consider buying one
http://www.pocketcannons.com/?gclid=CPrwneKz2McCFQenaQodS48NtA
http://www.pocketcannons.com/?gclid=CPrwneKz2McCFQenaQodS48NtA