Armed with detailed instructions and a whack load of marshmallow fondant, I created my daughter's cake over a couple of stages. The following photos are what I finally ended up with. The cake was finished on quite a hot day and the buttercream that I used to adhere the two sphere halves melted slightly and caused the cake to shift inside. By the time I served the cake the ball of yarn looked a little more slack than the photos. With a quick repair job with some additional fondant, the princess kitty was good to go.
If any of you are contemplating doing a sculpture cake I would highly recommend a Debbie Brown book for good designs and fantastic instructions. Just don't think about the obscene amount of fondant you will be using.
Next possible cake: a butterfly or a frog prince.