Not really a jewelry question, rather a foundry question. That
said… No one really casts pure tin, or pure copper, they may not
flow well enough to cast, aside from there being no application for
them. Pure lead these days is only cast for certain industrial
applications, for sinkers for fishing line, and for bullets.
Cast iron is a real specialty about which you’ll need to talk to a
founder who can do that. Maybe a sculpture foundry can lead you to a
cast iron foundry. I know there’s at least one bronze foundry in
Long Island City. The folks down at Sculpture House or at the Art
Students League should have an address.
Actually, your best bet might be to talk to the metal sculpture
instructors at the Art Students League. A few years ago they
completely refurbished the metal sculpture shop in the basement. If
you’re not adamant about using pure metals, then there are a lot of
casters who will cast white metal (a kind of high-grade pewter) and
various bronze alloys. Billanti Casting
Is very helpful to artists and craft jewelers. They used to be on
47th St. but have moved to New Hyde Park. As well as the precious
metals they cast in brass, bronze, white bronze and pewter.