I have some plans already drawn out (crudely) of how it would look/work. I will check the wiki (thanks for the tip) along with those links. I pray this isn't too amazingly hard for a beginner. I also hope this can all be obtained at a hardware store say for a modest price (about 30$ budget here).

I'm currently planning on making a pneumatic cannon that will fire either tennis balls or baseballs (or anything of the same size). I'm thinking it should be a 3 foot long PVC tube that might have a bolt to insert ammo (if it's too difficult I will just force it down the tube). I think it needs to r...