It's a safe bet that 3D printer aficionados would definitely own an industrial SLM (Selective Laser Melting) printer if they could, as the creative possibilities granted by them are endless. One such possibility is making actual working rocket engines, as Indian startup Othisis just demonstrated with a stationary test-fire of its fully cryogenic rocket engine, after a few failed attempts.
As a broad description, SLM printers work by depositing a layer of microscopic metal powder on a base, and then firing a laser that melts the powder into solid at specific places. The base then drops down a fraction of a millimeter, a new layer of powder is deposited, and the process repeats. All told, this results in layers around just 0.05 to 0.06 mm thick, made of metals and alloys that traditional consumer 3D printers can't quite handle. Here's an illustrative video of the process.
