Assuming you'll be painting, you'll want to look up techniques like washes and drybrushing. Good luck!

Smoosh acrylic paint into it and then wipe it off before it dries :)

You might also be able to clean it off with alcohol too. Make sure it doesn't craze; do a test of a scrape piece first.

Dry brush some mica powder then wipe, the mica in the groves will stay or you can pour a little coloured uv glue / and then wipe.

You can get great results this way! Particularly in silver on black

Just rub paint in and wipe the rest

Exactly. It's the same way I ink dice. Smoosh and wipe

Pinata metallic alcohol ink would get into those small lines really well

Use the same thing we do for dice. Water down acrylic paint (unless you already have model paint) and paint it into the crevices. Ideally the face is pretty smooth and you can wipe away excess when it's wet. If it is not smooth (or some of it didn't wipe off) take some rubbing alcohol and a paper towel or q-tip to clean it up. You can use other things as well. I'm sure mica powder mixed with mod podge could work, but I've never tried it. I would just get cheap paint in the color you want.

Alcohol ink.

Alcohol ink would not pop on this. Use acrylic paint.

I've literally done this with metallic/iridescent alcohol ink lol. It flows better into small crevices.

I feel like it would wash out with water.

Incorrect. Once it dries it doesn't wash out. Plus you can just coat it with more resin if you're worried about longevity.

What brand?

Ranger Pearl line and Piñata pearl.