I don't think I can do justice to a tutorial, but here's how I made the ring. The sanding really wasn't an issue, it was all done on the lathe, really. Here's how.
1) Start with a waste block of some sort fastened to a faceplate or chuck.
2) Glue a your ring blank onto the waste block using CA Glue or double face tape. I used a piece that was about 1 1/4"x1 1/4"x1".
3) I suppose you could either drill the inside of the ring out with the proper sized drill or turn it to size. I turned mine because I don't have a good 3/4" drill bit. I used a small scale spindle gouge to do the turning and I used calipers to check the inside size, comparing it to the inside of my wedding ring. I happen to wear an exact 3/4" inside diameter ring. I have skinny fingers [:I].
4) Hollow out the inside deeper than you actually want the width of the ring to be.
5) Once the inside diameter is taken care of, work on the outside of the ring. I rounded off the corners to give it a 'comfort fit'. At this point you can only do half or three quarters of the ring. The other half (the half that's closer to the headstock will be done in a little bit).
6) Sand the inside and outside of the ring (what you can).
7) Part off the ring, giving yourself a bit extra width just in case.
8) Turn your waste block or another waste block down to where your ring will fit snugly onto it. If you can turn something a little longer, it would be best. That way your hands aren't too close to the chuck or faceplate and you'll have plenty of working room.
9) Fit the ring onto the newly turned jam chuck. I decided to put my ring only 2/3 of the way onto the jam chuck and then tape the outside of the ring to the jam chuck to secure it.
10) Turn the rest of the ring to the desired shape.
11) Sand the rest of the ring, remove the tape and finish the outside.
I used a fine mist spray lacquer for finish but I would think that an epoxy finish would be best.
12) Do any touch ups that you need to on the inside of the ring. On mine, I realized that after finishing the inside with spray lacquer, it was too small for my finger. I ended up sanding a bit and then refinishing and it fit perfectly.
I'm sure there are other (and certainly better) ways to do this but that's how I did it. I can definitely see how using layered woods with alternating grain patterns would be beneficial. Or I could go the Boone route and use Titanium or Tungsten but I'll leave that up to Bruce [

]. As a side note, this ring actually broke/cracked while I was turning it. I was able to glue it and then I couldn't find the crack at all. I wore it for a couple of days and it was fine. My two year old really wanted to see it so after he had it for about five minutes I picked it up off the floor where it lay broken again. Oh well. I didn't think it would hold up too well but it was fun.
Hopefully that about covers it. Have fun and be sure to post your work!