Hey "Freak Style"!
Firearms must handle the extreme instantaneous pressure of a round
being fired. For the gun itself, the best material is hardened steel.
If I remember correctly, your necklace seller was struggling with
English. She may have been referring to the brass that makes the
cartridges ("bullets") that the gun fires.
While I can't give "recipes" for working with cartridge brass, I can
give cautions. Not all cartridges are brass. "Steel-case" means
exactly that. I've used aluminum case rounds in my pistol. Between
magnets and friendly gun dealers, you can cull the non-brass. Some
gun ranges sell fired brass, and you're certainly welcome to scout
the tables at a gun show, for a nominal admission fee.
Any cartridge you intend to work with must be expended! Look at the
butt-end for a central dimple where the firing pin ignited the
primer, and make sure the cartridge is empty and clean. Gunpowder and
heat are a deadly combo!
The projectile, or bullet, is the part that actually kills/destroys!
Some are lead, some "jacketed" with other metals. They are not to be
There are many kinds of primers, too. I know nothing about the
hazards attending to Berdan, non-corrosive, or other primers.
Or, you can scuttle all the above worry and just patinate some
brass/silver/nickel wire to the shade you desire. Look under
"bluing"! Check out products by Birchwood-Casey!
Be safe, and best of luck to you.
Dan - IJS