This video shows a little spring powered gun that I made with a Bic mechanical pencil. In addition to wooden pegs, it can also fire copper BBs and pretty much anything that can fit down the barrel. The pencil gun's firing mechanism is similar to that of some zip guns, except it directly hits the projectile instead of firing a primer and then a powder charge to launch the projectile. A quick note, sorry for the partially blurry video, for some reason my camera never re-adjusts focus while recording.