[facium]

I made a very simple single axis line plasma cutter once.
just a 110 plasma cutter, a threaded shaft (to move the tip), and a variable DC drive.

controls were simple limit swithches to prevent overtravel, and the dial on the drive.

what you can cut would depend on the table you build to go under the cutter.

If the rings are small you will get slag on the other side of the ring, but using a bar thru the middle of the rings should stop that.