As kids we took the empty brass ball-point pen refills, cooked the ink out of them and painstakingly loaded them with match heads and caps. Then it would be placed inside a piece of pipe and lit off. Pretty good little rocket. I still have a blue spot on my left palm where the ball blew out of one and lodged under my skin. I guess if I ever get in a MRI that steel ball is coming back out! Its a wonder any of us still have both eyes.