"Ultra-hard steel parts are now being 3D printed for military use: "The prototype printer, commissioned from 3D Systems in South Carolina for $15 million, can create objects up to a volume of 1 by 1 by 0.6 metres. The makers call it the largest, fastest and most precise steel printer ever made, big enough to print entire parts for military vehicles, such as hatches."
https://www.newscientist.com/article/2240724-the-us-army-has-a-3d-printer-for-ultra-strong-steel-gear-and-weapons/
https://www.newscientist.com/article/2240724-the-us-army-has-a-3d-printer-for-ultra-strong-steel-gear-and-weapons/