Cu 2+ (aq) - liquid core
The regular supplies have been delayed or missing for weeks, impacting your experiments (and the funding those experiments provide). You ran out of dissolved copper last week, and your other dissolved metals are nearly gone as well. Pounding feet on the stairs herald the return of your assistant, who wordlessly (panting) offers the requested handful of coins. They’re all old enough the metal content should be reasonably pure, and while it might technically be a crime to destroy currency, you can pay the fine with what you will forge from this metal. You gather your acid and peroxide and begin.
Turquoise transparen resin with copper foil around turquoise liquid cores with copper foil and a little holo flaky glitter, inked in copper. Video of the d20 in motion here.
More photos are available on twitter @cipherdice.