This is a Nemo cake topper I made for a Nemo's cake. Instead of doing it with rice krispies, I baked a 7" x 3" round cake (you could do a square if you want), and I just carved the cake to give Nemo's shape. Sorry, I forgot to take pics of all the process, but I will explain it as much as I can 

How I did it...steps:

1st- I cut the cake in a tear drop shape. I used some of the cuttings to make Nemo's round shape head on top. (this is where the round cake worked for me, because I used the round edge to place it on top of the head). Then I crumb coated the cake....

1149269_424877494298865_1378289047_o.jpg 166k .jpg file

2nd- I covered the cake with orange fondant

1149577_424877567632191_197473424_o.jpg 154k .jpg file

3rd- I gently pressed with my fingers where the eyes were going to be placed. Also pressed with my finger where the mouth was going to be...

1147718_424877640965517_641263991_o.jpg 176k .jpg file

4th- I used white fondant and cut the eyes in a kind of tear drop shape...and place them on the face

622406_424877657632182_9032981_o.jpg 229k .jpg file

5th- I cut the fins one bigger than the other and with a toothpick  I made the indentations to make them look real . I made an small cut in the fondant (cake) where the fins were going to be placed to help attach them

6th- I made the tail and did a small cut in the fondant (cake) to help me attach it.

7th- I cut 2 circular shapes for the eyes (orange) and placed them on the eyes

8th - I cut some white strips to make Nemo's strips and place them on the cake

19th- I used orange food coloring to emphasize Nemo's eyes, then black to make the eye circle in the middle, and finally a white dot to make the eyes pop out!

10th- I used orange food coloring to do his eyebrows, fins and tail

11th- I used black food coloring to paint the other details...

1149644_424877847632163_104722187_o.jpg 114k .jpg file

Well, that's the way I did it....it is my 1st time doing a 3D character, I hope that with practice; I get better at this! 

This is also my 1st tutorial, so I hope that this can be helpful....