I have been asked to make a 'dummy cake' like this. I was wanting ideas on what to use for all that 'snow'. It seems it would be a whole lot of fondant and I don't know if royal ising is an option? I want it to look soft. I have never made a dummy cake before either so outside of fondant I don't know what mediums will stand the 'test of time'. Ideas and opinions please? TIA

It looks like it's probably royal icing. It will keep for a very long time. I wouldn't put that much fondant even on a dummy cake. It would cost a fortune and weigh a TON!