On the subject of the rings in the Sundance catalog-- They appear to
me to have been made by a method that is very quick and easy if you
have the right tool.
You can buy a set of dapping-type tools that are intended (I think)
for making seamless bezels, round or square. There are graduated
tapered holes-- picture cone-shaped depressions in steel-- and a
matching punch. You would drill a hole in the center of the coin,
put it in the matching-sized hole, and tap it down with a punch,
yielding a truncated cone shape. In other words, a band that flares,
smaller where the center of the coin was, wider on the rim. Then you
either reverse it and tap til the ring is straight, or move it to
some other mandrel and mallet it til even. The metal will be much
thinner on the side that was originally the middle, as it has been
stretched quite a lot, but you should have a band that looks just
like the one in the catalog.
You could, of course, do this without the special tool, using a
mallet and a ring mandrel. It would just take longer. It occurs to
me that this could be a great project for teens-- maybe at a
birthday party! I can hear it now, like a woodpecker convention.