wow -- so cool --
for the square cake, the cake or cake batter that forms the planets is placed/ piped in a straight line right? surrounded by the chocolate/black batter --
so for a round cake, the piping goes around in a circle and the cake would be cut into wedges to show the work --
And make sure you line the layers back up properly if you are filling the cake! That would be easier on a square or oblong shaped cake. Does it HAVE to be round? Square or oblong would be sooo much easier I think, not having to curve all those sausages of cake or whatever is used into the batter...how to stop them sinking...I dunno, I have utmost respect for those who do surprise inside cakes, and I am sure they charge accordingly, so make sure you do too!
That is pretty cool looking with the planets inside the cake!!! Be sure and post a picture of your cake. I would love to see it!!!