The Sportsball pan will be way too small. Any ideas on how to make an exlarge beach ball cake? I thought about using a metal mixing bowl, but am unsure of baking time and temp for this. I think with an added layer in the center... this would be perfect. Any ideas?
My basic rule of thumb is that one cake mix (about 5 cups of batter) feeds about 14. Because round things have to be cut "funny", you probably get a few less servings, so I'd think that you'd need about 6 cups of batter per half of the sphere.
You can definitely bake a cake in a pyrex baking bowl and (I would think) a stainless steel bowl, but one issue you'll have is sag because of the weight of the cake. I even encounter that problem with the small sports ball pan. The weight of the top half of the cake and the icing will smush even the hardiest of cake recipes. I don't torte/fill them, either. Just a thin layer of buttercream to hold the 2 halves together and rolled buttercream to cover.
You may need to use a board to support the top half and some dowels in the bottom half, no matter how you decide to construct it (i.e. 2 half rounds or 2 quarter rounds with layer(s) between carved to complete the sphere).
HTH--please post instructions & pics when you're finished, too!