We have two methods of constructing a shipping container here. The photo above is using containers once used for rubbish collection. They lined with sand and a pool liner inserted over the top. Can’t get much simpler than that but the results for the neighbourhood are obvious.
The pool below utilizes a different method that I can only assume is a poly resin type coating coating the inside of the pool. It may outlast the pool above but not sure of the cost implications but either way both pools look great and would no doubt be a welcome addition to many a garden!