I made a Finding Nemo birthday cake cake for my son's 4th birthday party! The cake is four round vanilla cakes, all with blue colored cake inside to look like ocean water, blue frosting inside and out. I changed the shade of blues for all four cakes inside and all four layers outside, but the color change is not as obvious as I had hoped.
I started doing the fondant shapes days ahead of time as they were quite time consuming, but fun and gives you a chance to be creative making up your own sea life shapes. I just bought pre-colored fondant from Michael's as that was just easier for me and it is easy to use.
I used cookie cutters and fondant tools to shape fish, and all kinds of sea life fondant figures and then added eyes with gel frosting. I also read about melting starbursts in the microwave for 10 seconds and made some sea life shapes out of that as well. I did try to brush all the fondants with Crisco vegetable shortening to keep them from breaking, it did seem to help, but some things still broke.
The Nemo characters are plastic toys that I added to look like the real Nemo, Dory, Pearl, etc. I used the letter candles to spell out happy birthday and his name. I wasn't sure if I would use those, but by the time I added all the sea life there was not room for writing so glad I picked them up!
Of course I had brown sugar right there to add to the bottom to look like ocean floor once I moved the cake to the location of the party - and of course in all the party craziness I forgot to add it to the bottom of the white cake tray which would have looked so much better. But I do feel good, it was made with lots and lots of love for my sweet little boy!