I have wanted to make one of these cakes for a long time and finally a bride who is into nature - this was for her shower. 12 in and 8 in rounds covered in buttercream - "bark" was melted chocolate and I used a spatula to smear it on wax paper then cooled it - peeled off and attached to cake and smoothed buttercream over it. Used same melted chocolate to paint lines on the sides and made pinecones and pebbles out of fondant.