I have a fever, and the only cure is more RepRap.
This one brings up an important point. While Reprap machines are very inexpensive prototyping machines, there is still a long, long way to go before they help a creative person move from prototyping their ideas to actually creating economically viable short production runs.
Hmm.. Very good point!It seems you can do a lot of stuff with moulds and casting parts (though I have no experience with that myself) but it does limit the design options which kind of defeats the purpose.
Cast parts for Reprap machines have been made from time to time. They're typically one or another kind of polyester and tend to be quite brittle.