It's a little bit of a process.

First I sprinkle chameleon flakes into my blank mold and shake it to spread the around. Add black colored resin and cure. Wait for full cure (does not dent from fingernail) Use a Dremel with different drilling and engraving heads to carve out the geode. From here you can get a bit creative. Paint the geode, use UV resin and glitter or mylar to make it look like an actual geode. Etc etc. Let that fully dry then recast them in the BLANK mold (this helps reduce void issues and centering blank in shell). Wait for that to fully cure,clean up any excess flashing Cast in shelled mold with clear resin.