The previous owner of my house left this compost bin (if you can call it that). It's just some welded wire fence in a circle. There's no structure to it. It worked well for a while. I got a lot of good compost out of it last year and re-filled it over this past summer. As you can see, it hasn't held up.
I decided to build something more substantial. The previous owners also left an old swing. I cut it up and saved the 4x4's from it. Then I went to Home Depot and bought 2x4 lumber from the scrap bin. Most of it was warped and twisted and only 6 ft long. It was sufficient for what I wanted to do.
This is what I came up with. It has two bins. The plan is to fill one side and let it sit for a while and then move it to the other side.
I bought some plastic 1" netting and stapled it around the interior. At $20 it was the most expensive part of the project.
I built a removable door to hold the stuff in.
Bungee cords keep the door in place.
Here it is with one side all filled up.