I made the decorations myself. Basically you can get brown & white melting chocolate from the cake shops and use gel-based inks to dye the colors. Draw the design you’d like to use on parchment paper, using a pastry bag you can trace the outlines with the brown chocolate, then fill it in with the dyed white chocolate. Let it dry and turn it over. The flat side will be beautiful!

For this cake, I found a picture of Elmo online and drew it / traced it from that picture. I freehand drew the goldfish.

This book explains about the process:
The Whimsical Bakehouse: Fun-to-Make Cakes That Taste as Good as They Look!

If you like making your own decorations, I definitely recommend learning this method. It’s fun and the decorations are edible too. I also used it for this cake (My Little Pony).

Good luck!
Anastasia

The Whimsical Bakehouse

Basically it’s just chocolate (the melting kind you buy at
candy/cake stores) mixed with oil-based gel food colorings. Then
you use parchment, trace the outline of the decoration in the
brown chocolate and fill in with the colors, and when you turn
it over, voila!

I definitely recommmend the book – it’s really fun.