Back maybe 25 years ago I got to tour inside Howmet in Muskegon, MI as part of a class. They did casting of turbine vanes for jet engines. Damned impressive process, and thorough quality checks x-raying every one for flaws. Finding out that each vane has coolant channels cast in was interesting, and a bit unnerving, since they get operated at temperatures above the melting point of the metal! I always think about that when I get on a plane.