Just wondering if anyone can give me some direction asap! I am making a cake in the shape of a helium filled balloon. It has to feed 35-40 people so I used a 12" round cake pan.

Any suggestions on how to get the 'ballon' shape as well as suggestions on making the seam around the balloon? Also, the cake MUST be iced in buttercream and not fondant, however fondant details are ok.

I have googled balloon cakes, and found very little except for the usual red blue and yellow 'latex' party ballon cakes.

ANY help is most appreciated!!!!

Thanks in advance!