I needed several cod fish to place in the bottom of an O scale rowboat. I saw several photos of fish online that looked as though they might work. I copied them, reduced their size, duplicated the image several times, and printed them out. Next, I glued the printout to a thin sheet of soft foam (made for the scrap-booking crowd) and coated the fish surface with Mod Podge to seal it.
After the gloss medium dried I used a spade blade in an X-Acto knife to remove each fish. I thinned the back of the fins with the spade blade and then painted the edges of the foam gray.
The last step will be to flex each little fish into a football shape and give them another coat of gloss medium.