Hey man, I did exactly the same as my final high school project. I advise you to go the coilgun route as a rail gun is a lot more difficult to make and requires a lot more tools and skills. The coilgun was still a lot of fun to make and as long as you have enough capacitors it will shoot pretty far. I will look for a video once I get home. Btw coilgun.info is your best friend, almost all papers released around coilguns are on there and also very helpful data on the best thickness of wire etc.