When you get a chance take a look at what AMAVF is doing!! They just reported great numbers and they can 3D print with different metals!
Sentiment: Strong Buy
i don't get why people think 3DS can't print metal.
google "3D systems sPro 250 Direct Metal"
The printers I've seen all just print one material. There are printers that print only concrete, printers that print only stainless steel, and the majority print plastic. A printer able to print several different metals is definitely an improvement.