Here is my finished Planes, Trains and Automobiles cake!
I did a "road" out of crushed Oreo cookies for the automobiles, a little cone and racing flag on the road, and there was candy that looked like rocks (from the candy store) in the center of the road circle, holding the candle up.
I added a train track made out of black licorice for the train to ride on, along with a "R X R" sign.
For the airplane I pinned him in with some toothpicks and covered those up with cotton candy that looked like clouds.
The frosting underneath it all was very sweet and sugary, not your typical butter cream frosting. I am still looking for the perfect birthday cake frosting, but this would be really good for a fancy occasion--like a wedding cake. It also comes out extremely white (although I dyed it green to look like grass). Click here for the recipe. I also have some more pictures of my fondant images here and the recipe for the marshmallow fondant (what the images are made from) here.