The Navy cares about this technology because its fleet is aging, with ships dating back decades. Many of the parts that make up these vessels are so old that substitutes are no longer manufactured, and replacement parts have to be custom-designed.
The Shape Of Water
https://www.youtube.com/watch?time_continue=2&v=vrbNBiTZk5c
Just a decade ago, the idea of 3D printing metal parts directly from a computer file seemed like science fiction to many people. But the technology is quickly growing up. There are few better examples of its promise than the GE Catalyst, a new advanced turboprop engine GE Aviation started testing in December.