Well i tryed this experiment a while back about a year and i have to say its quite fun. And let just say i went to extremes, i made an electromagnet and used two rc batteries and about 15 ft of 12 gauge copper wiring and a nice big 7 inch steel bolt. for the track i used some carbon fiber tubing cut in half(very hard to cut in half) and i used pachinko balls two on the projectile side and one on the other. I flicked one pachinko ball down the track hit the one and shot the other pachinko ball on the other side super fast. I use to have a pachinko ball stuck in my wall about half way until my dad saw it and yelled at me. then he gave me some puddy and paint and told me to fix it. Looking back at it i really wish i had a camera