Super Soaker Central

http://nerfhaven.com/forums/index.php?showtopic=21433

Everybody in the thread is like, "OMG, a homemade pump. I don't think that has ever been done before!" anyway, the thing looks sick.

Wow, that is a lot of info to digest in one reading. Looks like it would only work for pressurized reservoirs, ie pumping air, not water, but again, that is a lot to read, and I may be mistaken.