We used to roll wire or rod around pipes or tubes into coils and then cut it into rings.
If you drill a hole in the tube or pipe and put a 90 deg bend on the end of the rod it will hook so you can roll it around the tube or pipe. I would try a pipe or tube about 7" in dia as the wire or rod will swell after it is wound to a larger dia.
The wire torch holder on my welding cart shown here was rolled with the same method.
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