My son wanted a train cake for his 4th birthday. I have a mini loaf pan that is similar to a cupcake pan because it makes 8 cakes at a time. I baked a mini loaf for each child in his preschool class, plus an engine and a caboose.
It took 2 boxes of cake mix to bake 16 "cars" and the front of the engine. To make the round cylinder for the engine front I filled a small tomato paste can 3/4 full of batter. It took about 10 minutes longer to bake than the mini-loaves.
I crumb frosted (put a preliminary layer of frosting) on all the "cars". I used star tip 16 and star tip 21 to cover the "cars" with stars. I used a few other tips for other details, and to make each car unique. One car I dipped the top in graham cracker crumbs to make it look like sand.
Another car I covered in Nerds to make it look like coal. I softened a Tootsie Roll in the microwave for a couple seconds and rolled it flat to cover the top of another car. The six girl "cars" were made pretty with flowers and pastel colors. The flowers are made from royal frosting and left from a cake class I had taken.
The caboose I frosted red, then used black gel for the windows and door details. I softened two cherry Now and Laters and stuck them together before placing them on the top of the caboose for the upper windows.
To make the engine, I cut the rounded top off a mini-loaf, then used frosting to hold in place the cake cylinder (from the tomato paste can) on top. I added another trimmed mini-loaf standing on end to the back. I used toothpicks to help secure the pieces together. After frosting the engine, I placed a silver chocolate Kiss upside down for the steam funnel. I used more black gel frosting for the final details.
I used round mint candies for the wheels on all the cars and lined them up end to end on a long piece of wood. It took me all day to frost the 14 different "cars", so give yourself lots of time! My son loved his cake!