BWL, thank you very much for introducing me to the idea of making a very strong part using the flexible mold process! The prototype of all kinds of parts could be made of easy to machine materials, then reproduced with JB Weld. I also liked how the plexiglass head illustrated the mind blowing, to me anyway, rate of discrete explosions characteristic of the internal combustion engine. Imagine the scenario of a Formula One engine of the 1990's running at up to 19 or 20 thousand RPM.