The rims of my first tables used wagon wheels my then girl friend, now wife, found in our tecks in the mountans west of Boulder, Colorado. They were easy to find in the '60s, not so when I started making tables again a few years ago. We had a bunch of whishkey barrel hoops from a planter that fell apart and they worked well for rims. But 20 to 30" diameter circular tables soon got boring!
After a couple of years of thinking I finally figured out that thin (1/16") cold rolled steel could be bent to follow the outline of square, oval, or irregualr tops. One of my colleagues suggested that I could get the patina of an antique wagon weel or whiskey barell hoop with a little acid on the steel and a little time in the back yard.
I now make my own rims. The table I call Knab Oval features a slab of picture sandstone from quarries near Knab Utah surrounded by Lyons sandstone from quarries near Boulder Colorado. These slabs are glued to and oval slab of 3/4" plywood with the thin steel rim attached by 1" screws. The spaces between the sandstone slabs is filled with black grout. The top and rim are sealed with an oil based sealant.
As of today (9/4/21) this table is for sale, and I have several more slabs of the Knab sandstone that I would enjoy incorperating into a table top for you.