This folks did such phenomenal work with economic and humble materials, now imagine if they had the budget to afford high end material in the U.S, the result would be beyond jaw dropping.😮😮😮😮😮
They didn't have to nail it down, because it wasn't going to move. Once you make the box and bolt it together like that, you don't have to worry about anchoring it to the ground. It will stay in place, since it will be filled with water.