It's been done, a guy called Funky Diver made one and it's spot on. he doesn't play tournies though so not sure about the legallity?I was looking into an idea of strapping some sort of feeder on your back with a tube & a unit that will hold approx 2000 paintball & off you go. No need for a hopper attached to your marker, just pull & go...
Don't know if it would be tourney legal