Got a new HF spot welder for Father's day today. No more plug welding rails which I have become good at, but no more. Its a bit tricky with a small gas wirefeed.
I tried using tubing, 1/2 inch soft copper from the hardware store was too springy. I bought a same length of 3/8 inch and slipped it inside. It works well. I reused the tip of the HF spot welder, but if I were to do it again I think I'd use MIG tips.
Better would be a length of Type M hard copper tubing, if you have a plumbing supply in your town they should be able to fix you up.
I found a guy that sells that same tong on another forum for less than I could I could make it for.
I bought one and it works, which was a surprise to me.
But this tong really works; AK Hunter1 says it is hard copper tubing with heavy copper cable inside. And it has a MIG welder tip that is replaceable.
He sells extra tips too. Here is the link.
The Guns Network LLC ~ Discussion Forums - WTS Spot Welder Tong
One thing about aluminum. As it gets hot it expands and then shrinks when it cools.Make sure you check your connections for tightness once and a while.
I know this is a very old thread, but Type K copper is thicker...used for water supplies and such. If making a tong using cable and tubing, use the Type K.