Large rings for use in a rotating compost trommel

I want to make one of these, but I'm having trouble sourcing large rings to serve as the frame. Standard recipes call for bike rims, but I can't find any in my area and I don't want to downcycle perfectly good rims from a working bike. I've also seen culvert piping used, but I don't have any and buying that new is expensive too.

What else could be used to make a round frame?

"I can't find any in my area"

This is where I usually try a request in my local facebook community group. I've had all sorts of things; blocks for a building project, plants, seeds, wood chips by the truck load and my best was a mantis tiller if full working order for very cheap!

I've seen 5 gallon buckets being used as the ends of a trommel.  If that's too small, those blue plastic 30-55 gallon drums would be perfect.  Or a 55 gallon steel drum.

Barring that, can you get some thin metal from a big box store and make it into a loop?  If a guy had enough bendy willow branches he could maybe craft a strong hoop from a bunch of them together.

would metal culvert pipe work? or a more general term is 'corrugated metal tubing'. there would be some width to it, but I don't know if that would be a good or bad thing. the sizes I found through just a bit of looking ranged from 12" diameter up to 24" diameter from big box stores, to over 100 inches in diameter from special sellers.

sections of 24" corrugated metal tubing a few inches tall are sold as fire rings, if you didn't want to try cutting it yourself.