My mum had just returned from a trip to Australia, so I made her and 'Aussie hat' cake for her birthday. I used an old cardboard envelope covered in foil and then green roll out icing (I didn't quite have enough, so it was stretched too thin!) to make the brim. I wanted the brim to look quite floppy. The corks are made of marzipan and are attached to the brim with string. Mum was delighted (she really liked the little koala and I think it now lives on her mantelpiece).