Yea that paintball rail gun is actually real old new to the paintball scene. Back to topic, We need some one who will make a A rocket Launcher that shoots fire works. i've been thinking about it for a while. but before you get into any massive construction of this launcher, you should test ways to make sure the fire work will consistantly shoot and not get lodged in the Pipe and basically become a flame thrower or grenade. Safety first.
Oh yea even though you see the paintball rail gun working and functionally and you want to make it shoot paintballs there is one problem that could stop you dead in your tracks, that is timing. otherwise you'll b e chopping paint so badly you wont need to buy spray paint.