mixing clayRecently I have completed an earth oven that was made with clay purchased from a pottery supply store. The clay was extremely easy to work with. We mixed it with a hoe, one part clay with three parts sand in a wheel barrow and it was much, much easier that stomping the clay to smithereens with one's feet. The cost of the clay was minimal ($30.00) and the consistency was excellent. Building a circular oven with a 31" floor diameter, 15" dome height, 4" thick walls, we used about 125 pounds of clay. The type of clay we used was fireclay (Hawthorne 40 mesh). If you happen to live in Maine, you can buy it in Portland. However, with kids present, you might want them to do the barefoot-in-the-mud dance.