If you want to create things in metal, there are folks using PLA plastic to do investment casting. DavidF from the SeeMeCNC forum is (as far as I know) the expert on the matter. Check out his process, it’s pretty cool! http://forum.seemecnc.com/viewtopic.php?f=41&t=5986
There was also a recent King of Random episode about it (using styrofoam, though), and I also found this HackaDay article: http://hackaday.io/project/2434/logs
I don’t know if I can share any specifics or not, but another one of The MakerHive guys is even formulating an SLA resin for investment casting.
Has anybody here done any metal casting? From a 3D Printed part? Please share!