I spent over an hour hobbling around the pumpkin patch on a sprained ankle, searching for a matched set where one had an overbite and one an underbite. But the shapes aren't at all obvious in the final carve! Also, when I fit them together I bent the upper one to get it over the stem of the other, and then I was afraid to take it back off. So I carved all the teeth and eyes with them already stuck together.