The bender comes with two dies-- one is 1/2 round or low domed and
one is flat. I change them in accordance to what it is I'm bending.
It won't fit exactly, but getting close helps a bunch. I know of
people who have cast their own dies in bronze to reduce scarring or
even to more closely approximate a particular ring contour that they
make a lot. Carving and casting these dies would be fairly simple.
(The problem w/ bronze dies is that they, themselves, get dinged
Other than that, I sometimes put a matchbook or old show card in
between the die and the ring-- as I do when using ring bending or
hollow chop pliers. "Tuff Skin" sheets would also work.
There is a perception, I think, that some jewelers have that highly
polished tools such as bezel and prong pushers shouldn't leave marks
on shanks, heads, settings, etc. I just figure that bending heavy
stock or forcing over bezels and prongs is going to leave marks...
Removing them is part of the process. Of course, the fewer marks that
you put in the less you have to remove. And textured shanks present
problems. Still, the best bet that I've found is to select the die
that most closely conforms to the cross section or contour of your
shank and then cushion the die with a match book or show card.
Take care and hope that helps,