I would recommend meeting up with someone who has experience and knowledge in Lost Casting as you can read about here.
http://www.instructables.com/id/From-3d … plaabs-me/
Here's a very informative video https://www.youtube.com/watch?v=WWVVSZP3Au4
This method would be more steps, but if you are doing a limited run of parts for machining (tool/die) purposes, this method would let the parts last much longer with the right metals being used. Smelting can be very dangerous if you don;t know what you are doing, so please be extra careful and do your research if you are attempting this.
My experience: I've made several leather working stamps for a buddy of mine. I designed and printed them, then he cold casts them with whatever steel is cheapest or available at the time, then makes custom purses, belts, satchels, etc
Printit Mason and Printit Horizon printers
Multiple SD2s- Bulldog XL, E3D v5/v6/Lite6, Volcano, Hobb Goblin, Titan, .9 motor, Lawsy carriages, direct Y drive, fishing line...the list goes on
Filawinder and Filastruder #1870.....worth every penny!