I made the unicorn cake topper out of marshmallow fondant.
¼ cup shortening
1 (16 ounce) package marshmallows
4 Tbsp water
1 tsp vanilla extract
2 pounds confectioners' sugar
½ cup cornstarch powder
Place the butter in a shallow bowl, and set aside. Grease a large counter top with butter to work on.
Sprinkle the marshmallows with water and place them in a large microwave-safe bowl, and microwave for 2 minutes stirring once in a while until it is all melted. Mix vanilla extract into the hot marshmallows, and stir until the mixture is smooth and sticky. Pour half of the powdered sugar on the greased table, spread it out.
Rub your hands thoroughly with shortening, pour the melted marshmallow and begin kneading the sticky dough. As you knead, the dough will become workable and pliable, about 10-15 minutes. Add more sugar as needed to form a firm dough.
Form the fondant into a ball, wrap it tightly in plastic wrap, and refrigerate for a few hours or overnight. To use, allow the fondant to come to room temperature, and roll it out onto a flat surface dusted with cornstarch powder. Place it over the butter cream frosted cake. Gently pull the edges, smooth it out with your hands or a piece of fondant to get rid of any air bubbles. Trim the edges. Decorate it with desired decoration.
The fondant is good for up to a week in the freezer.
Color the fondant into desired colors, roll out on a sugar dusted surface, wrap on the butter cream icing, then mould the eyes, ears and other decorations using your creativity, just like you would do with a child's play dough. Enjoy!