If I were to make a 3d cake say a pig laying down and I used the 16 inch oval pan how do I stack the layers. If I want to stack four layers on top of each other what do I do to keep the bottom layer from being smashed?
You could put the top 2 layers on a cakeboard (cut to your cake size) then dowel the bottom half and stack, just like you would do if it was a multi-tiered cake. I would also stick a piece of fondant on top of the first layer so when the top is taken off after cutting the frosting doesn't come off with the cakeboard.
a less expensive option to keep icing from sticking to cake boards is to use "Jimmies" or sprinkles.