There have been a couple of articles on soft jaws in the ME press last year, one replicating the standard chuck jaw, and the one I saw recently which is simple and very effective using hex bar.
I found a length of 11/4” hex bar on ebay for a few quid and had enough to make four sets of jaws, should keep me going for a few years. The hex’s are held on to the chuck jaws with grub screws, very useful for those odd shapes or skimming thin discs.
Mike