I do heavy duty electrical work and use 1/4 x 4 copper buss bar. I clamp the workpieces by sandwiching them between a central bottom piece and another piece along each side. I welded the length of my fleetside tailgate in a single pass with zero warpage. I takes three peices of copper, but it works really slick. The bonus is this: a near perfect finish on the underside. I guess any heavy gauge copper will work. grin


They named it Apache cause it has a patchy welded here and a patchy welded there.