This reconstruction of Heron's steam ball is made of copper, brass, lead / silver solder, and a small amount of Teflon. The Teflon was used in the pivot joint to overcome friction between the revolving sphere and the steam pipe. The caldron and the ball are made of copper. To achieve the bowl and sphere shapes, I used a process called metal spinning. This involved placing copper sheets on a lathe, against a form. I used a steel ball bearing soldered to a steel bar to push (with all my brute strength!) the spinning copper onto the forms I made out of hardwoods At first, I made things that looked like cymbals (what was supposed to be the caldron) and footballs (the ball), but with practice, I achieved the end result. The top of the caldron, fittings on the ball, and the ring stand are made of brass. I used the band saw to cut out the circles, legs, and fittings and finished them on the lathe to make them smooth. The caldron, brass top, fittings (with small pieces of Teflon), pipes, sphere and outlets were soldered together in the form seen. The final product was placed on the brass ring stand I constructed. I included a minor design change: I drilled a safety hole and plugged it with a cork on the top of the caldron to allow excess steam to escape under extreme pressure.
Lloyd, G.E.R.; Greek Science After Aristotle. 1973. New York.; W.W. Norton Company, Inc. pp. 100-106.
James, P. and Thorpe, N.; Ancient Inventions. 1994. New York.; Ballantine Books. pp. 131 - 133.