The OP, @arvanlaar
, has two separate threads going about the ring. The other thread is about gluing brass and wood together. The OP asked about finishes here. Other people have recommended a CA finish. Most people use ordinary CA glues as both adhesive and finish. I have done it myself many times.
I want to mention GluBoost Fill 'n' Finish products, which is CA designed to be used as a finish. It is not that special or different than other CAs, but the differences are enough to convince me. I switched to GluBoost CA finish for pens. Read the instructions carefully - they recommend putting the thin over the regular, which is not "standard." I switched to GluBoost because:
* GluBoost claims that their CA finish is flexible. Flexible is better - it is less likely to chip or crack in the future.
* It is easier to smooth out compared with other CAs that I have used. Ripples, waves, and other undesirable defects are less likely.
* The activator does not leave white spots or hazing. It stays clear. I tried to make it haze by performing a "heavy spray" test, but failed. Their claims are valid.
* I think that the GluBoost finish looks more sparkly and clear than other CA finishes. Maybe I am susceptible to their marketing hype, fooling myself just to rationalize the purchase, so take that for what it is worth. It certainly doesn't look worse than other CAs I have used for finish.
Rockler recently added GluBoost to their shelves. I decided to give it a try when I noticed it at my local store.
When arvanlaar is ready to apply a finish, I recommend attaching the ring to a slowly rotating tool to help apply and smooth the finish. He doesn't have a lathe. A drill press running at its slowest speed might work, but I would try to spin the ring in the vertical axis, not horizontal like a drill press. Do you have a benchtop drill press that you can rest on its side? I know someone who made an improvised lathe that way. (His friends and I pitched in and bought him a real lathe.)
An electric hand drill might work at a low speed. My hand drill has a switch for high and low speeds. Maybe a friend can hold the trigger on slow while you apply the finish. Don't even consider using a dremel tool.
Try it out on scrap first. When you are ready to do the real finish, keep in mind that if things go bad, you can always sand it and try again, but that is not best practice. The sanding scratches in the finish will disappear when you apply fresh finish, so don't panic.