Angle Iron. Three separate pieces sold as a lot. Curved. Rolled to 4' diameter circle. Industrial grade flange. I got it back in the 90's from a cousin that repaired cement trucks. I told him I wanted to build a fire pit. He took it from the scrap pile but we never came up with a full circle. Not even a half circle. I think maybe a welding artist may find this useful.
Each side leg is about 3" by 3". I measure about 5/16 thick. probably closest metric mm equivalent.
If you had to buy these retail? Forget it.
Pick up near Cretin Derham Hall High School in St Paul Zip 55116.
Cash only.