Before I made it I did a few rust experiments. The results here.
Step 1: Initial polish
Doing this will make it eaisier to polish towards the end.
Step 2: Cut the groove
First I marked the pipe with marker. I followed that mark by scoring a line with a pipe cutter. Next I used a carbide bit to cut the initial groove. I expanded the groove with a round hobby file.
Step 3: Refine the ring
Safety First: Use extreme caution if you use a lathe like I do. You have to understand what angles are the safest when using a file on a piece that’s spinning at 2500 RPM. Just incase you hit the chuck you want it to deflect not get bound up. Always work within your experience.