Whew! The face is done, now it's time to bake your cake, let it cool completely, then pop it into the freezer. When you're going to sculpt cake it's absolutely necessary to freeze it first, otherwise you'll have a huge mess!
Be sure your cake board is strong enough to carry the weight of your cake. In this tutorial I used heavy foam core (about 3/4" thick). You don't want to use anything that will flex on you.
I use an 11"X15" Wilton sheetcake pan for this cake, but using the next size up... 12"X18" is a better idea. This will give you more scraps to play with. I had some trouble using the smaller pan as I nearly ran out of scraps to play with. I think my cake would have looked better using the 12"X18".
The 11X15" cake pan takes 2 boxed cake mixes, the 12X18" uses 3. If you're making your mix from scratch, just double it for the smaller pan and obviously triple the recipe for the larger.
When you're cake is out of the oven and completely cool, take a cooling rack and place it on top of your pan, tip the cake upside down and onto the rack. Then, clean your pan. Once the pan is clean, cover your cake with wax paper, allowing the paper to hang over the sides. Now, place the clean pan over the top of the cake. Pick up the rack and pan together, turn over allowing cake to fall back into the pan. Then, cover the extended wax paper over the top of the cake. Cover the entire pan and cake with another layer of wax paper, then a good wrapping of plastic wrap. Don't go lightly with the wrappings, this will prevent freezer burn!
Freeze your cake for a couple hours or until frozen. I've made the cake several days in advance of the construction before without problems, so if it's Tuesday and Your party is on Saturday, you can bake and freeze today no problem.
Before you cut your sheetcake, you may want to score it. I've tried to show my scoring marks in this photo. Score it so you'll have a total of 3- 4 3/8" pieces, this will leave you with a strip of cake at the end that you'll use later.
The scored cake in this photo is an 11"X15", if you use a 12"X18" (recommended), your scored cake will look different.
Shaping Your frozen cake in just a few steps. The best advice I can give here is to study your model and try and duplicate the look by shaving away at your stacked construction using a sharp knife. I recommend shaving just a small amount at a time. You'll see in this frontal photo that I've shaved the cake to make it look rounded on the sides. I've also left a base at the front of the cake, which closely resembles that of the model.
Use your extra strip to build up the back of the cake, build a smokestack and whistle. This can get messy, but once it's frosted will look great.
Remember, there is no right or wrong way to do this. Originality is a wonderful thing! My photos are only to be used as a guide and it's important to note that I moved my scraps around a bit before settling on how to place them. You may find a bit of gaps from one photo to the next and also see that there is a lack of transition. Sorry about that! As I make more cakes I will develop a proven system, but for now I recommend having fun with it and allowing your own creativity to guide you.