SpudFiles

You could build a shell out of candle/bee's wax and fill it with the same paint that is in a paint ball. The shell will either launch or bust either way you;ve got a paint mortar

Not really into paintball but there is a feild across the street at the park, bet I could sell some to the guys

i know i am way late on this but its a very good idea exspecialy the ball valve some one was talking about all you would have to do is exstend the neck a little and ad the ball valve.
you could use that to control the air leak too