In this tutorial I'll show you how to make a Mad Hatter's Hat Cake Topper. It can be used as a decoration or a top tier. If you want the hat to have cake inside, simply substitute the polystyrene with cake.
5.
Roll the green sugarpaste to about 4 mm thick. Apply a very thin coat of water on the dummy (take excess off with a paper towel if there's need). You can use glue or piping gel if you prefer. Cover the dummy with sugarpaste.