Today is my daughters 15th birthday! This is the cake I made for her. I used the ball pan, which was perfect, rice crispy treats for the legs all covered in fondant. I was told I needed to use a dense cake or the ball wouldn't hold it's shape, so I did a little research and it seems to have paid off. If you ever want to make a box cake mix more dense all you do is add a box of pudding and use 1/2 the oil and 2 TBSP less water(I used white cake with lemon pudding). Make sure you tap the pans on the counter and bring the air bubbles to the surface.
The legs took a full batch of rice crispy treats. I molded them last night and used foil to help them keep shape. We lost some form over night, but that was okay. I would recommend letting the treats sit over night and then shape it again to get rid of as many bumps from the rice crispies as possible. I've also coated the treats in warm fondant to fill in the holes, that works well too.