Here is my semi-finished pond. Due to a mistake I couldn't alternate the length of each board. So I went ahead and built each side up equally. I used long lag bolts with washers to attach the boards. Basically what I have is 7 wooden rings stacked on top of each other. I then lined the inside walls with sheets of plywood and screwed them to each ring. The bottom was covered with sand. After laying the liner inside I screwed some 1x6 deck lumber on to the top, over the liner. After that I trimmed the liner back. Next, I plan on adding a simple lattice roof to give some shade. As you can see my lilies came back to life.