What fires 20mm balls and is completely homemade? Nope, not the $500 rubber band gun. Jörg Sprave’s gatling gun sling shot. It’s a completely hand crafted affair and works in the most rudimentary of ways. A crank rotates the barrel and a small piece of wood forces the loaded ball over a threshold thus releasing the tension and firing it off into the yonder. It can fire up to 960 rounds per minute, though it’s magazine is only good for 8 shots.