Fondant often is used in cake decorating because it produces a smooth finish on the cake, which looks professional and elegant. However, many people do not like the taste or texture of fondant. You can achieve results similar to a fondant-covered cake by smoothing the buttercream icing with a lint-free, soft cloth. The cake icing will look smooth, as if the cake had been drizzled with a river of smooth icing.
Cut the soda bottle into a rounded rectangular shape about 6 inches wide and 12 inches long.
Wash the soda bottle with a dishwashing soap and allow to dry.
Freeze the cake in the freezer for one hour.
Cut off the sharp edges of the cake with the serrated knife.
Apply a thin layer of buttercream icing all over the cake to make a crumb coat.
Apply a second layer of icing to the cake, about 1-inch thick on all sides. Try to smooth it as much as possible with the spatula.
Pull the bench scraper along the sides of the cake at a 45-degree angle to smooth the sides.
Shape the top edges and sides of the cake by smoothing the round side of the soda bottle over the cake for additional smoothness. Discard any excess icing that you remove in this step.
Allow a crust to form on the icing. This can take up to 30 minutes.
Touch the cloth to the icing in an inconspicuous area. If the icing does not stick to the cloth, then you can proceed.
Place the cloth on the side of the cake. Carefully smooth the icing with a fondant smoother or your hands.
Move the cloth to a new area and repeat the process.
Place the cloth on the top of the cake and smooth the top and corner edges.
Use paper towels if you don't have a suitable cloth to use.