I made a thin sheet cake for the bottom and frosted it with a gray buttercream frosting for this Optimus Prime Transformer Cake. The transformer is 9 X 13 cake that I cut apart for the transformer cake. I had a couple of pictures for online to use as a guide; and first cut apart a piece of paper to use as a template.
Before frosting each piece I froze them, to make it easier to frost and then, started putting them together, from the center out. The ‘rocks’ on the bottom are some rock candy gum my kids had. I also warmed in the microwave some tootsie rolls and shaped them into the tires and exhausts that he has on his arms and legs. Once they were in place I frosted over them.