Additional "frosting" ideas

Another "frosting" for prop cakes is Paintable Bathroom caulk. It can be airbrushed or dyed before applying. It will pipe through a pastry bag, although roses won't get as crisp an edge as real frosting. Will not crack or break at all if dropped, and if dyed before applying can be washed if it get's dirty. If you are trying for a fondant look, apply the caulk as smooth as possible, give a few minutes to start to firm up and using water and the palm of your hand for edges, smooth caulk until desired look. Make sure you give the caulk a chance to dry slightly between smoothing passes so it doesn't just wash away. I have had great result with this technique and the cakes last "forever".