For this train cake, I bought 6 mini loaf cakes (queen cake, but pound cake would also work). If you want to take the time to bake, you can also make the mini loaf cakes. If the cake has a tendency to be crumbly, freeze it before working with it. I sliced off the top mounds of 5 of the cakes so that I had flat train cars to work with. I cut the sixth cake into three, and stacked one piece on a whole cake to make the engine, one on end on another to make the caboose, and sliced the third piece in half horizontally and placed it on another cake to make a slightly raised goods car. [Alternatively, you can buy 3D cake pans from Wilton or Nordicware. There are some cool things available!]
Now the fun part -- decorating!
I made buttercream frosting and divided it into 5 bowls, then colored each bowl a different color (I chose blue, yellow, green, brown and red). Whatever colors you choose, just make sure they are bright and strong! Each train car was then frosted a different color (don't forget to crumb coat first!). Place them in desired order and arrangement on a large platter as you frost.
With white icing, I piped the outline of doors, windows and bumpers on the different cars. With a larger tip I piped yellow icing in lines between the wheels.
The wheels were chocolate sandwich cookies (Oreos or something similar), stuck directly onto the icing.
With a dab of icing, stick M&Ms (or Smarties or Rockets or Skittles) onto the center of the wheels. Yellow and red ones can be used for the train headlights and rearlights. Remaining candies can be pressed into the icing in whatever pattern you like.
To connect the train cars I used chocolate Pirouettes. Any kind of chocolate or dark round or long rectangular sweet you can find will work well as the connecting tongues (licorice, for example).
Now for the train cake toppers!
The engine needed a smoke stack, of course! For that, I used three marshmallows, mounted on a bamboo skewer, and rolled in decorating confetti balls (you may need to moisten the marshmallows slightly).
Being a steam engine, it needed a coal car. Chocolate puff cereal made excellent lumps of coal, piled on within a piped rectangular "coal holder."
An animal cage car seemed in order as well. (I guess this was really a circus train cake!) Animal crackers were stuck in the middle of the car and candy sticks were used for the cage bars. The roof was a bar of chocolate (it got a bit heavy, to it might be wise to bolster the cage with long skewers at the four corners).
The next car was just a great place to carry "balloons" or wrapped lollipops, and the final car, the caboose, just had a lot of candies stuck all over it, with another chocolate Pirouette on the back as a rear bumper.
This was my little one's first 3D birthday cake, and he was enthralled! He spent the morning leaning on the table gazing at his cake. I call that a success!