I was able to make this Baby Einstein Caterpillar Cake for my son's first birthday with the helpful suggestions of several other people on this website.
I used the Wilton Sports Ball pans for the body of the caterpillar and cupcakes for the feet, tail and antenna. I used Cake Doctor cake recipes to make strawberry, chocolate and butter cakes. Two of the cakes were chocolate, two were butter and the last cake was strawberry. I used the remaining cake batter to make the cupcakes needed.
The Wilton cake pan instructions say to bake the cake at 325 for 18-20 minutes. I baked my first cakes at 325 and they took almost an hour before the center was completely set. The next cake I tried baking it at 350 and it still took almost 45 minutes but the center fell in (not a big deal since the cakes were laying flat on the board). So based on my experience I would definitely go with 325 and just bake it as long as is needed to get the center done.
The party was on Saturday and I made the cakes on Wednesday (after they were cooled I wrapped them in plastic wrap and they stayed incredibly moist).
I made the frosting and decorated the cake on Friday. It took 3 batches of buttercream to frost the cake. I tried to do pull-out stars (Wilton #16 tip) for the body of the cake but my buttercream was too warm and it started to melt together. The frosting ended up looking pretty cool though because it had a fuzzy look to it. I frosted the head, feet, tail and antenna in a smooth finish. It took me about 2 hours to frost the cake but I had already spent an hour that morning mixing my colors (using Wilton color gels). I bought the Wilton cake icing gel for the eyes and mouth.
The cake is much bigger than I imagined. I put it on a 20x30" foam board covered in foil. My son and guests loved the cake and it was really fun to make although a lot of work.