I have a Stud Welder that looks like an Oversize gun that leaves studs (they look like nails) welded to the body. I then use a dent puller to pull on the studs. Finally I grind off the studs.

The one he uses that intrigues me is like a stud welder that has a slide hammer built in and the stud is part of the gun. He welds the end of the apparatus to the body, slide hammers it and then twists it off.

Here is a picture. I am not even sure what to call it, but I want one.