The foundry is a high-temperature furnace for work a Smelter cannot do. It makes exotic alloy from exotics and steel plate, superconductors from exotics, wire and coolant, and shielding from exotic alloy, composite, ceramic and exotics.
It is built from ceramic, composite, coolant and pumps. It draws more power than any other facility while it works. Only a foundry works can hold one.