Chisel and a hammer. Metal cutting bandsaw if you have (or can rent)
one. Typically, those ingots come pre-formed into one pound lumps,
strung together sort of like a hershey bar. You could just try
breaking it off in a vise at one of the one-pound joints.
You are aware that this stuff won’t handle or cast anything like
silver, right? It’s intended for costume jewelry, and will melt at
some incredibly low temp. (compared to silver at 1700F.) It’ll also
contaminate all your tools, so you’ll have to clean your files & etc
before working on silver again. (The crucibles will be fatally
contaminated. You’ll just have to get new ones.)
From your note, you’re talking about “small sizes that I can put
into a crucible” which leads me to think that you’re thinking of
casting it as if it were silver. It’s not, and it won’t act like it.
There’s a reason those ingots are pre-notched into one pound blocks.
Costume jewelry people tend to do large loads, with a very funky
centrifuge caster that uses huge disk-shaped vulcanized rubber molds.
White metal casts at a low enough temp that you can shoot it directly
into a rubber mold. Very, very different beast than “precious” silver
If you’re looking for something “cheap” that does cast
(more-or-less) like silver, try Rio’s antique bronze. $12 per pound,
instead of $20+ per ounce, and no worries about contamination. It’s
not nearly as liquid as silver when molten, but it does have at least
a faintly similar performance envelope. (Molten silver flows like
milk. Bronze is more like maple syrup.) If you can get your molds to
work with bronze, they’ll be a cakewalk with silver. That tin stuff
won’t tell you anything about how the mold would work with a precious