I got a piece of a cedar tree from a job site.
It's probably 18" around and I cut it, er, uh, I mean I found it and it was about 18 inches thick.
It works great for what little I throw at it. Mounted it on a 4 x 4 post, put a piece of conduit in the ground on the side of the house that had an ID just a bit bigger than the 4 x 4. I shaved the edges off the post with a planer and it just slips right in. Get done, pull it out and don't have to worry about weed eating around it.
I should dig that out and maybe practice a bit again.