Continuing to think of what material to use for vise jaws. I have some electrical copper bars, looks like 3/16 thick, that would work for soft vise jaws.
To keep them on the vise, I could weld some copper to the back to look like "ears" to hold the jaws.
So, obviously, the strength requirements are minimal. Just keep the jaws from falling off when the vise is opened.
The question is, can this electrical copper be welded at all.