Make an Inflatable Bladder

Another link from Cottonbuds, this would be a great project to make for the kids. This site shows you how to make your own inflatable bladders. What's an inflatable bladder you might ask, "You can make inflatable bladders for pool toys, dolls, balls or even kites and it's really cheap." More than just a bag you blow up and tie off, this one has a valve, you use a soldering iron to put it together, and the site has instructions to do your own minor repair work.