Made this for our management period review meeting at work. Tractor is made of RKT, didn't realize that if your using them for structure you shouldn't put butter in them to they dry more firm. First trailer was a triple layer Vanilla chocolate chip cake with Vanilla buttercream and chocolate chip filling. 2nd trailer was lemon cake with lemon curd filling and lemon buttercream. Not quite what we envisioned but I think my husband and I did pretty good job for 3 days of non-stop work on the cake. My husband made the wooden base for the tractor and trailer to sit on as well as the RKT tractor and the gumpaste tires.