A foundry was a type of factory dealing with metals and alloys.
Lillias was a foundry worker on a Nezu colony planet in the Delta Quadrant, until her region was decimated by an series of Etanian-caused asteroid attacks. Lillias took shelter in a non-functioning mag-lev carriage, and when Lieutenant Tuvok and Neelix came to repair it, she noted as a foundry worker, her expertise was not in mag-lev carriage repair. (VOY: "Rise")