You may want to look into the custom keycap community, the've been putting 6mm figures into custom keyboard keys for a while now! (no idea what resin they use though)
https://www.reddit.com/r/keycaps/comments/swsbub/epic_40k_space_marine_keycap/
Very nice thanks!
Jdiction deep pour. Do not use art resin. It is meant for thin pieces. They don't yellow over time like some do.
Thanks. I am looking at encapsulating 6mm mini's so it's not a deep item, but thanks for the info.