I printed the light ring.  That's what I'm going with.

It was too small because I modeled the strip length based on the outer surface, I'm actually using the inner surface, so.. the strip is too long and doesn't fit.  It's important that the strip goes all the way to the end in my ring as I'm already down ~2 LEDs and about 70 degrees from the gap required to clear the arm.

Instead of reworking the model math to fix my error, I just added a negative offset to the variable which held my end clearance to match how much more length I needed.

I also tested the mounting slots, fitting them to my newly printed mounting arm wings.  The light ring split along the layer lines fairly easily.  I made that area thicker, wider, and taller in the model, so my weight is now up to 1.3 grams.  

Mounting the tabs into a channel on the surface with super glue instead of modeling a proper socket would probably work better here and was actually the original plan until I got going on the idea of a socket.  

I reprinted the ring with the length and socket changes.  

The strip length is right now, and the socket is strong enough, but it is a real pain to clean up.  Short ledges right next to short bridges doesn't work so well.  I was thinking about going back to the surface channel/super glued version, but then snapping it on and having it stay put was a little satisfying.

Time to sand it and give it two coats of paint, on the outside.  First coat will be white primer so the inside doesn't turn black as it's so thin, then over that will go some black camo paint to reduce the light going through it.

EDIT: My painting sucked, so just reprinting it in black and calling it good.