Absolutely – in fact it is quite common. With the advent of several television shows showcasing decorative cake making, peoples’ expectations for the visual impact of cakes is increasing. Having some of your cake as fake (ie. polystyrene) is a good way to save money on the cake itself and spend more on the decorative aspect. If you are concerned you will run short of cake you can arrange for some ‘slab’ cakes to be delivered separately to the venue and cut up for guests. Guests will not know the cake they are given was not part of the display cake.