Well, I had a fun day. Worked on the bass drum and drove the car while glue set up.
I ended up making six strips of maple 1/32" x 1.5". I actually cut a 45 degree angle on both ends of each ply to fit against the 45 degree cut on the existing ring. The first strip, or ply, was not glued to the shell. I glued the second ply to the first on using several c-clamps then repeated for each additional ply after about a half hour or so of glue setting up. Once all plys were glued up I took the curved piece of wood to my edge sander and sanded one side down so all pys were flush. I used that edge for the inside. After a little work with a small drum sander and lots of hand sanding I was able to copy the profile of the existing ring. Glued in the piece, did a little more sanding, paint and there you have it. Someone had painted the area of the shell where the ring was missing at one time, they got some paint on the edge that I should remove.
Last pic shows how close and precise the new ring came to the factory edge. I was very happy that I was able to do all of this and leave the round factory edge untouched.