Each child is working on a building project. Here is Ben's water wall . Thank you for the idea "frugal fun for boys". It was too hard for us to nail the bottles on after our layout-so luckily Rhet got home early before our interest dropped. Unfortunately, it was right when I was holding his new nail gun and air compressor. Uh oh. Who was I to know that you don't use a nail gun for this kind of project?