That's a pretty glaring omission. I imagine the prints look pretty awful, but it a neat idea. In the normal use a wire feed welder the arc (bright sparky part) would be uniform to create a bead. From what I saw in the videos they are using a "bad" welding technique that would build up the instead of penetrate the metal. They will need to replace/control the wire feeder and the voltage of the welder in order to better results.