Hi Daniel, I would first unsolder the bands. Next work on each one
at a time, working from the inside then the sides then the outside
in the following steps: Place the band on the mandrel, check that
the inside is perfectly round, hammer as needed (be sure to keep
them all exactly the same size). Next, check the sides making sure
the outsides are perfectly parallel, hammer and file as needed.
Last, mark the sides all the way around with your dividers and file
any high points, filing around the ring rather than across, hold the
ring up to the light and look at the profile from all directions for
any imperfections. When all three are done, then solder them back
Hope this helps, sounds like a neat project with the runes on there.