We had two different versions, a flat one made out of a sheet cake cut to the silhouette. The second option is a 3D cake carved out of several round cakes.
The main body is (depending on the total size- this is the smaller version) an 8" round cut in half to make two semi-circles and stood on end (that's the back/butt area) then a 6" round is also cut in half and placed on either side to make the legs. These pieces have icing between each layer to hold them together.
The head was constructed out of another 3- 6" round cakes and the snout is a cupcake. To make the head is um, difficult. It doesn't necessarily work the same every time. Stack two of the cakes against the 'body' and look at it. What you have to do is cut some of the bottom cake off so that it sits flush against the 'body.' The part you cut off will most likely be at a diagonal on one of the edges. (Somewhere I have a photo of it before it is iced, that would make a lot more sense!) If you have the part of the cake that is usually cut off (that top 'hump' part), it usually makes for a good forehead.
The cupcake snout sits in front, laying on its side. You might need to cut some of the side (which is now the bottom) to keep it from rolling.
The important part of this cake is using the cake icer tip (tip #789). Put the serrated side down (to grip the icing to the cake) and cover the entire cake with rows of icing. THEN you smooth it out and pull off the extra icing. Using the large tip is a must for working with butter cream. It keeps the crumbs out of your cake, which is a huge obstacle with carved cakes.
The ears are actually cardboard, cut to size, iced and decorated and held in place with toothpicks. (toothpicks are tucked into the ends of the ears and then placed in the cake.)
Draw on the eyes, ears, hooves, nostrils, and use a star tip down the back.
This basic design can be used to make the 'red velvet' armadillo (which I have done- make the nose a bit different, add a tail), it can also be a bunny rabbit (again, different nose, add a fluffy tail). Frog? You bet it could. I think it would take one fewer cake for the head, and you would have give him some little front legs, but that's about it.