I'm working on a baseball-themed cake and wanted to incorporate an actual baseball (it's only a half-ball because in the end it'll look like it's stuck in the grass). When I was making the main part of the cake, I set aside some batter to make this ball. Here is the pan (or rather, pans) I used:
On the left is a 4" pan and on the right is a 4" hemisphere pan, both by Fat Daddio's. These are some tremendously sturdy pans; they weigh a ton! And, of course, each of these pans comes in a variety of sizes. I greased and floured the hemisphere pan and filled it about halfway (roughly half a cup), then dropped it into the 4" pan and let it bake about 15 minutes (whenever the toothpick came out clean-ish).
fondant, somewhere around 1/8" thick:
AmeriColor Gourmet Writers), thinned royal icing colored with AmeriColor's Super Red in a bag fitted with a round #3 tip, and a dusting pouch filled with a 50/50 mix of powdered sugar and cornstarch.
You can see it peeking out from behind a fondant pennant on the final cake in this shot: