First I cast a bottom piece. Thanks to the Z-Butt community, I learned to get the petri effect, you need to wait for about 1-2 hours before adding in alcohol ink to the resin. Here I waited for 1.5 hours.
After the bottom piece is cured, I add a polymer clay fish. I use acrylic paint to add details and dab a dollop of resin to secure the fish to the base. When everything looks dry, I invert it to cast the top piece.