Being able to 3D print metal in a hobbyist setting, that is cheaply and effectively, is very likely the next milestone for 3D printing as a whole. Putting the means to create your own engine parts is a way off but that day is getting closer.
Witness this metal-printing robot arm, a creation born from the joint efforts of AutoDesk and a Dutch designer, called MX3D-Metal. It’s a slightly more cost effective way of printing with metal, though not quite up to the standard that will eventually be required for its use and you would still need to be able to afford a complete robotic arm to do all of the heavy lifting.
At present the MX3D-Metal is able to print strands of metal that cool fast enough for the created structure to support itself immediately. The folks behind it are obviously looking to do more but this could be just the thing for the computer-savvy (the software is custom-designed) metal sculptor in a hurry.