If you have a plan to give a birthday cake for your boy you should consider a train cake. Since the train is great transportation there are a lot of boy likes the train. To make a train cake there are several ways. The first way is by using train topper and the second way is by making train-shaped cake. Here are several kinds of train cake ideas that I found in the net to help you exploring your idea if you willing to make the cake.
Source : Train Cake