I am decorating my cake in a few hours with basic buttercream icing. My figures and details are all made with MMF enhanced with gum-tex. The figures have been dry and very hard for a few days now. I have never worked with it before so I am not sure how far ahead I can place the details on the cake. They will be sitting right on the buttercream. I don't plan to put the cake in the fridge if that makes a difference. Should I wait until the last minute to add the details? I was thinking of placing everything tomorrow morning before I leave with the cake. We won't be cutting it until around 2 or 3 pm tomorrow. What do you think? I am just dying to get the details on it and see the final product. Patience is not a strong quality of mine LOL

P.S. The icing has a small amount of 5% cream in it to thin it out. My basement is fairly cool so I am storing it in a box down there. Will that be fine until tomorrow? I read that the sugar is enough of a preservative even if the icing has a bit of cream in it.

The only times I've had problems with figures on buttercream wilting/collapsing is when I've made the mistake of putting the cake/s in air-tight containers. Keep the cake in an open plastic container (either in the fridge or out at room temperature). Or a closed cardboard box is fine, because it's not air-tight & the cardboard draws some of the moisture.