I'm in a university paintball society. We were considering using reballs as the uni was happy for us to use them in their gym halls. We'd have committee members there to sweep the used reballs to the side after each game, and cleaning them is as easy as dumping the used ones in a tub of water, rolling them about, then scooping them out for re-use. We were gonna go ahead, but then the uni took our start-up money back to help their finances...