The first two layers are constructed from an every day sheet cake. Put one layer down. Fill with frosting and put the other layer down on top.
Step 2: I need support!
Before the lens layers go down, what I did was make a cardboard cirle the same size as the pan. I covered it with tin foil and then stuck skewers into the cake to support the heavy lens layers that went on top.
Step 3: I can see clearly now...
Next to layer are the two little circle cakes that will be our lens. A layer of frosting goes in the middle of them to help them stick together. It's all coming together now.
Step 4: Brrr.... It's Frosty!
Next give the entire cake a crumb coating of regular (tinted or not tinted - doesn't matter) frosting. This will help to make sure that none of the little crumbs dislodge from the cake when you give it a coat of color.
Step 5: Makeup!!
After your crumb coat is dry, you can start applying the color. Tint your frosting with food coloring to the color you need. I've found black concentrated gel made by Wilton. If you don't put a lot in white frosting, you wind up with purple! - please see pictures for proof. All the details were applied with a icing bag and cone tip. (tip... the poor man's icing bag is a zip lock baggie with a little hole cut at a bottom corner - I use this frequently).
Step 6: Lastly...
Take pictures of it and then destroy it... with your mouth! It's as easy as pie,... errr... CAKE!