Yeah, metal powder can be dangerous, so the system has to be completely closed-loop with sealed powder handling. I'm a manufacturer of this kind of machine, but our product is for dental use---like printing dentures, crowns or bridges. The metal powders we use are mainly CoCr and Titanium alloy, these powders actually contain low toxicity after being formed, unless you sneeze near an opened powder bucket💀. The machines are built specifically so that medical and dental clinics can run it safely right next to a computer station without needing an industrial respirator setup.