The steel almost nobody can make.

Grain-oriented electrical steel, or GOES, is the material at the heart of every large transformer core. It is a silicon-iron alloy at roughly 3% silicon, rolled into sheets 0.18 to 0.35 millimeters thick, with the crystalline grains forced into a specific orientation called the Goss texture, named after Norman Goss, who patented the process in 1934.