Here is a kit that turns robot arms into metal 3D printers. The Meltio Engine enables robot arms to create highly complex models. It comes with integrated lasers (1200W). It can handle stainless steel, carbon steel, titanium, inconel and other materials.
This 3D printer can be upgraded with a hot wire, external wire drum, and powder feeder. Meltio can integrate with robot arms with at least 20kg payload. The below video shows it in action.