It’s a pain. The way I do it, and I’ve built almost 10 tables in the last few years. Two hole saws. Cut your outer diameter. Two screws on either side of the pilot hole to hold the piece to another piece of plywood, use smaller hole saw and cut again. One failed ring for about every 4 or 5.
For my next table? Hold the line…
3D print the SOB’s…
No 3D printer? I have a piece of 4” PVC pipe. I was going to chop saw the pieces or build a quick miter box for a hand saw and cut them. I was also going test the pipe with a jumbo drink holder but finished the last table before I did.
Either way, they’re essential, impossible to find, a PITA to build, but there are solutions.
I have two builds upcoming for this fall so I’ll get a chance to try the pipe and the 3D printer deal.
Never drink the koolaid… Tables without rings would be horrible.
Good luck.