DIY 3D printers aren’t that difficult. It’s just two or three motors, a motion controller and a hot nozzle for most plastic printing. Replace the not nozzle with a really epic laser diode for metal parts. Even better with lithographic printing minus the really toxic fumes of the material. Take a really bright high resolution screen or maybe a projector and one motor and you got yourself a lithographic printer. Are you going to compete directly with cutting edge printers? Probably not. Will you still be able to make shit that works? Most likely after some tinkering.