My daughter requested a Unicorn Rainbow cake this year for her 5th birthday. The rainbows and unicorn are gumpaste, sprinkled with disco dust. 10-8-6" layers--yeah, I made too much cake. ;-) I tried the aerosol luster dust spray for the first time on this cake, and though it doesn't show up well in this photo, it works gorgeously. It's more subtle than I thought, but I certainly could have continued to add more layers to get a more dramatic effect; I just wanted a subtle shimmer.