We started by taking one of our favorite vintage cast iron pans, a beautiful Wagner from the 1930s, and going to visit some foundries.  We were told that there was no way that a modern foundry could pour iron that thin.  Not willing to accept that answer, we stumbled on a whitepaper called Thermophysical Properties of Thin Walled Compacted Graphite Iron Castings written a material science professor in Europe.  We emailed him and he agreed to Skype with us.  He was eager to help and more than a little amused.  With his help, we were ale to perform microscopic imaging to compare the graphite structure of vintage pans and make sure they weren't black magic.  Eventually, we visited his lab to learn to make iron castings by hand-the way our favorite pans had been made over a hundred years ago.