The swan is a favorite photo that I shrunk down to size to fit inside the box. For the fish and starfish, I stamped them onto plain white cardstock in black ink, then heat embossed them, colored each piece, cut them out, and pressed the finished side onto a Versamark pad, and then into a container of UTEE (ultra thick embossing enamel), melted the enamel, dipped it again in UTEE (three times total) to get the glossy shine. (Here is a video on how to do this.) I put rhinestones as eyes for the fish and a centerpiece on the starfish, and "bubble" stickers to mimic water bubbles within my scene.
The top of the box. I painted the outside of the box, and lined the inside with leftover Japanese paper.
It was fun doing this shadow box, and I'll probably do another one at some point.