Joel - tumble finishing is pretty straightforward.
For castings, first you need a medium to heavy abrasive media then a
finer abrasive media. Follow with stainless steel. If your pendants
have some texture, that should be the end of it. If they have broad
shiny surfaces, you need a final step with some kind of wood or shell
mixture charged with chrome oxide or Simichrome.
All of the stuff except the steel can be run in a small vibratory
tumbler. The size of the tumbler will influence finish quality and
running time. You need a rotary tumbler for the steel.
Unfortunately, doing it on the cheap will cost more because you will
eventually want to get the right equipment anyway.
Tumble finishing will soften edges, but not nearly as much as using a
buff. If you omit the abrasive steps and use only steel - you will
get a shiny rough surface, kind of like using rouge without tripoli
I wrote a small book on the subject - “Tumble Finishing for Handmade
Jewelry” that pretty much covers the basics. Rio Grande sells it.
Judy Hoch www.marstal.com