Tina -- What a nice idea for your son!

You might want to take a look at Wilton.com. It is full of great ideas and pans.

Wilton has a cake pan that has a ghost coming out of a pumpkin. It also has directions to make a little boy with a baseball and his arms spread wide.
Click here and scroll down (to page 2) to see a sample.

Wilton also has a cupcake-like pan for making mini ball forms.

They also have sports ball pan set with instructions for making baseball, soccer balls, etc.

They also have a soccer ball pan that could be converted to a big baseball.

Wilton also has/had 3-D baseball cake with a baseball in the glove. I could not find this pan on the Wilton.com site, but I see many available for sale on other sites.

Let us know what you do so we can all benefit from your experience.

Hope this helps. Good luck to you. Kelly~WA

Editor's note:
Ball Cake Pan - Stand Up Ball.
Instructions for baking and decorating sports ball cakes