My client's instructions were to combine all of her nephew's favourite things -- swimming; Curious George; and his giraffe stuffie -- into one huge birthday cake.  

Starting with a sketch I began to form the cake piece by piece...

And the finished product! Curious George swimming cake complete with splashing water, a pool floaty for George and water wings for his favourite stuffed giraffe. Safety first kids!
 

Curious George has gone bananas for, well... BANANAS!

I don't always do a sketch before starting a cake (e.g. when someone wants something super specific, like a Boba Fett helmet), but I always find it fun to go back and compare the finished cake with my original brainstorm to see if they are wildly different.  Sometimes it's just a matter of getting carried away and adding more details than I originally planned. Other times I make adjustments based on how the 3D version is coming together... if I don't like the composition or colour schemes, I make adjustments as I go.  This one came pretty close though!