Foundries make metal parts: they use sand and ceramic materials to make molds and cores to make those metal parts. Sand molds and cores are made by a variety of processes, from green sand to no-bake and beyond. Cores are made through a variety of processes, too, some with tooling and some by hand. Pretty much all the processes require some form of a solid pattern.
As time goes on, the tools that are used and the sophistication of the media continue to improve. Through all o