Keep Truckin’ — How to Assemble an 18 Wheeler Cake

We receive all sorts of cake requests, some examples are for dogs, cats, dresses, burgers, sushi and all modes of transportation! Recently, we made an 18 wheeler semi-trailer cake for a metal company. This step-by-step tutorial is an easy way to build any type of car or truck cake.

Before you begin, be sure to use a nice dense cake and a filling that isn’t too soft — like  buttercream. We like to bake the cake the day before we carve it, so it sits in the refrigerator overnight. It is much easier and less crumbly to carve a cold cake! Once it is filled, we cover the cake in buttercream to create a smooth finish before we cover it with fondant.

Instructions — 

Step 1:  Carve and fondant the front of the truck. We put our cake on a custom cut piece of medium-density fibreboard (MDF board). It is cut into the shape of  a rectangle with a thin rectangle piece that sticks out. This helps us assemble the back of the truck.

Front of Truck

Step 2: Pre-cover your cake board with fondant. We used an impression mat to make it look like asphalt. We then cut out a piece so that we can glue down our support piece of foam. It should be shorter and thinner than the actual truck so you cannot see it from either end after it is assembled.

Precover your cake board

Step 3: Glue down the support piece of styrofoam. On top of the foam, glue down the front part of the truck. We also added a piece of foam core for the trailer to sit on.

Glue down support piece

Step 4: Glue the  back of the truck down and cut out the wheel holes. (It is important to pre-cut rectangles out of your baseboard so that you can easily carve out the wheel holes). Then, add  gumpaste tires. (Be  sure to make these ahead of time so they are nice and dry!)


Step 5: Add gray strips with paint or airbrush silver to create the details on the back of the truck.

Assemble Back Panel

Step 6: Use an X-ACTO knife to cut out the fondant for the windows. Insert thinner pieces of gray fondant to create the windows. Be sure the cake is cold, or the buttercream crumb coat will come away with the fondant when you cut it.

Front of Cake

Step 7: Add details such as mirrors, wording, bumpers, reflectors, etc. to create your finished truck!

Truck Cake