George :

Can't help much as I don't have the plan worked out. I have been thinking about buying what is called rigid plastic netting. It comes in different mesh sizes , lengths and widths. Large offshore pens are made from it for growing salmon. I have thought about taking a strip 6 feet wide and long enough to make a circle 20 feet across, covering the bottom with the same and attaching flotation to the top and using a light mesh top for easy access. With this approach you can make it what ever size you want with little or no corners to deal with. Just thinking out loud. ewest