These are my compost bins. I made them out of fence wire and sheet metal. They are all 3 ft diameterl. I have tried different diameters and different heights. I use to have some 4ft dia and 2 ft dia. 3ft dia is working best for me now. If you double the diameter volume increases about 3 times. I use to have some 4ft tall but the 3ft tall is easier for me to work with I am getting older my back is not as good as it use to be I don't want to be lifting heavy loads. The sheet metal compost bin was made from a sheet metal counter top cover the metal is 26" wide 10 ft long. I have 3 sheet metal screws holding it together where the ends over lap it took 10 minutes to build this. The other 2 compost bends are fence wire. This wire comes in rolls with several different widths and lengths. Farm supply has 50 ft and 100 ft rolls. Garden supply has 25 ft and 50 ft rolls almost double the price of farrm supply. I cut the fence in 10 ft lengths over lap the end and tie it together with wire it takes about 10 minutes to build one. The fence wire comes 3ft tall, 4ft tall and 6ft tall. The compost bin that is almost full was filled last fall with grass clippings, garden left overs, tree leaves, apples from the apple tree, kitchen scraps it was filled in October so it has not composted much yet. I use to have these at the other end of the garden in full sun they composted much faster in full sun. I am planning to move them back to the other end of the garden this fall. A roll of 50 ft long fence wire 3 ft tall is $39 at TSC it will make 5 compost bins including sales tax they cost about $10 each.