Themed cakes usually have a unique shape based on the scene or image you want to create with the cake. Any rounded or arc shape, such as a head, sunrise, rainbow or most animal bodies can be made using part of a round cake as the base for the shape. A sports field scene, geometrical shape or odd shapes like a musical instrument, are usually best cut out of a rectangular or square cake.
Get a picture of the scene or object that you want to make into a cake or a cake that you want to copy.
Trace the outline of the cake on a piece of paper.
Determine if the main shape of the cake is rounded or with angles. The main shape is going to be the largest shape when you look at the picture. Draw that shape inside the traced cake.
Determine the shape of the remaining pieces of the cake. If these pieces have angles, they will need to be cut out of a rectangular cake. If they are rounded, they will be cut from a portion of a round cake. Section off the pieces that you will cut from the rectangular or round cake and draw in these pieces on the traced cake picture.
Determine what shape is needed to make any two dimensional shapes on top of the cake. If they are small circles, use cupcakes, if they are squares or rectangles, cut these from any excess cake you have.
Make a list of the cakes that you need based on your drawing.
Bake the cakes on your list and allow them to cool to room temperature.
Place the cakes in the freezer for an hour to chill them on the outside surface, so that they do not crumble when cut.
Cut the cakes in the pieces as determined by your drawing and piece them together on a cake board. Place the cakes back in the freezer.
Crumble excess cake and mix it in a bowl with equal parts of buttercream icing to make crumb coating.
Take the cakes out of the freezer and fill any holes or seams between the pieces with the crumb coating by spreading it on the cake with an offset spatula.
Ice the cakes with buttercream icing while they are still chilled.
Bake one 20 by 20 cm (8 by 8 inch) square cake and one 20 cm (8 inch) round cake.
Chill both cakes in the freezer for an hour to avoid crumbling when cut.
Using a ruler, measure 10 cm (4 inches) in from one side of the round cake to determine where the middle of the cake is. Cut the round cake in half.
Place the square cake on a cake board with one corner pointing up. Place the two halves of the round cake on the top sides of the square cake to make a heart shape.
Crumble excess cake and mix it in a bowl with equal parts of buttercream icing to make crumb coating. Fill the seams between the square and round cakes with the crumb coating and ice the entire cake with buttercream icing.
Train shaped cake
Bake a 22.5 by 17.5 cm (9 by 13 inch) cake and two cupcakes. Place them in the freezer for an hour to cool so that the do not crumble when cut.
Cut the cake in half lengthwise. Cut one half in half again. You should now have one long rectangular shape and two smaller rectangular shapes.
Ice the long rectangular piece and place one of the smaller rectangles on top of one end so that the corners line up exactly on where the cakes are stacked.
Ice the top of the small rectangle and place the other small rectangle directly on top of it. Ice the small rectangles.
Trim the muffin top off of the cupcakes and place them back to back on their rounded side directly in front of the small rectangles that come off of the top of the cake. The cupcakes make the engine front of the train. Ice the cupcakes to match the rest of the cake and add detailed icing to make the cake look more like a train.
Use the crumb coating to make any detailed lines or shapes on the top of the cake or to help create a two dimensional image on top of the cake.