I would think that the amount of copper would be minuscule and be nothing more than a slag floating on the surface like a skin.

your right. from my experience, I melted down about 3 dollars when i was a kid using my moms grill and a soup can, the zinc liquifies and drips to the bottom, and the copper remains on top as slag. before i fully understood the fluidity of molen metal i tried to make a few things with wooden molds, unfortunatly, i never made the molds big or deep enough to work.

Hey boys did'nt yo mama teach you nuthin!
cheap Zinc = old carburetors etc.from a junkyard!ask for scrap zink/ called pewter it refined circles!
casting keys for decorative purposes does'nt require purity only apearance!
Bayer silicone's have products that will deat with the heat from zinc casting see if they have an agent in your area! As you should not be concerned with total dimensional stability on these keys you could ask for product that has reached it's use by date or even expired product if it is out by 2% so what!
Lost wax, for decorative castings where absolute tolerances are not important(like keys for decoration)you can use gypsum(plaster of paris)as a first and second coat bake out in an oven and then set these in sand. Cast your keys from wax in silicone moulds.
Good luck with this. If you need any advice on this, please don't heasitase to ask!
All the3 best Ian

thanks for the support, like i said i don't need to make these for a long time yet, but i wanted the info now to tell her if i though i could or not. ill probably be making these sometime next year as i will be going to bootcamp within this year (hopefully) so the info is much apreciated.

I just saw this post, using 3/8 x1 you can make blanks pretty easily, this stock will produce a jailers size key,
Maybe 4" if this is good let me know, but smaller stock may work,

<div>look in metal sculpture sect. for the forged key, &nbsp; blanks are not to difficult</div>