We had a guy in high school that was good at welding them. He never stretched one, always got one that was too long and cut it down. Made the cut near one end. I don't know what he used to align for welding, I would assume some angle for a big vee block setup. He also used a stick welder, home mig welders were unheard of then.
I would think the thing to do would be to find someone that had too many, get them and practice.
