I am very excited to learn of an effort to build an open source EBM 3D metal printer :
http://reprap.org/wiki/MetalicaRap
This technology is currently offered commercially by Arcam AB.
EBM fabrication is rather amazing. It can make fully melted metal parts from STL files.
I am planning to build the superconducting polywell in titanium using Arcam’s process. It would be amazing to eventually have a Makerbot for metal.
Additionally the EBM device itself has much in common with a fusion reactor. Both use high vacuum, electron beams, high voltage.
I’d be happy to help this project with any vacuum, high voltage questions.
Prometheus Fusion Perfection 
fantastic! I built one of the first working makerbots and it is a lot of fun. I have often wondered if there was some path to printing in metal.