disneyfamily.com and found their Finding Nemo Sponge Templates and they worked perfect. I just had to add the embellishments to make them look like the characters. For Nemo and his dad, I just cut one smaller.
I think you'll find them pretty easy to make for your kids. Yesterday when I delivered my first two books with finger puppets to the hospital, the nurses were having fun playing with them so I'm sure the kids will too!