BAKING FOR EVERYONE - Renshaw want to be part of your baking. Work until plyable, roll out using a small amount of icing sugar. HOW MUCH DO I NEED?. - For a 5" tall cake rolling to 2mm thick: for a cake 4" width: 250 g, 6" width: 400 g, 8" width: 500 g, 10" width: 750 g and a 12" width: 1 kg.