A few years ago I designed several swings that I made from plumbing materials. I went down to the local plumbing store and bought 3 large standard sized pipes (9ft) that were hollow inside and 2 matching elbows. We put them together and then dug them into the ground about 2 to 3 feet depending upon how large we made the swing set, we poured concrete around the poles and allowed the concrete to cure over night. They were then painted with a paint that is safe for children. Here are a few pictures. It's really easy to make and kids not only love the swings they love climbing up the poles.
