4) Color black and grey fondant
For the grey and black teeth background, knead two small balls of fondant and tint one ball grey and the second ball black. Use black icing color for both; use just a little to make gray. Roll out both fondant colors. Using the paring knife or pizza cutter, cut one grey rectangle the same height as the bottom cake. Next cut one black rectangle one inch narrower than the grey rectangle. Adhere the grey fondant to side of cake on a diagonal angle with buttercream icing. Again using icing, place black diagonal over grey. Trim excess on bottom of cake.