The paint store pigment trick is a great tip. I’ve also used a squirt of Testor’s Craft Acrylic with no trouble. I wouldn’t gob it on for a full opaque pigment job but that’s probably not the best idea even with ‘real’ resin pigments. At some point it will decrease the material properties of the resin - epoxy or poly.
The thing is practically done. I made a lot of mistakes, especially in the lamination (the tail was more difficult than I thought), but given the total lack of experience in everything related to board building, it even turned out pretty. At least I think it will work! Painting helps to disguise my mistakes