This fellow made this engine by hand using lathes and such. No CNC machines. It took a year and a half.
http://www.wimp.com/tiniestengine/
http://www.wimp.com/tiniestengine/
Yea... Seen that before. It's pretty cool and I won't take that from the builder, but (not to burst your bubble) it isn't internally combustible. It just spins under air pressure coming from the hose. There is, however, a huge subculture of people that build ones that DO run. I will see it I can find the link.
When back in the 50's folks would work on their rides , and gather in White Castle or a similar spot , the coolest car I remember was an
MG TD that kept the hood but with the side panels off one could view the polished aluminum of an OFFENHAUSER!