I'm using the wonder mold to make a tiffany lamp cake. I found a cake plate with pedestal (pedestal for lamp base). The problem is that the plate part is not flat, it's slightly domed and is 8 inches. I know the wonder mold is 8 1/2 inches and hoping for some shrinkage or I'll trim it. But how do I fill the area? Do I use extra cake? I don't know if the cake will hold it's shape if I just place it on the cake plate. If I use a cake plate on top, how do I adhere it so it doesn't move? Will hot glue keep it in place and stick to glass as well as a cake plate?