Bench vise soft jaws

You can also make them out of scrap copper. If you know of or are "friendly" with an HVAC/R outfit, see if they have some scrap copper tube. You can anneal the hard copper then just clamp a piece in the vise and hammer form it to the jaws, trim the access etc. And as above---you can do the same thing with scrap aluminum. It must be soft, and I'm no expert on aluminum alloy