I want to make a space themed birthday cake for my son, Owen, who will be turning 4 the end of this month. I am VERY MUCH a beginner at decorating cakes and have never worked with fondant. I would be appreciative of both ideas for his cake and pointers.
You could do a rocket shaped cake like this: http://www.flickr.com/photos/alis_cakes/5072863651/
There are instructions in the Planet Cake book. You could either use a football pan or carve the shape yourself.
You could probably do this came design with buttercream with fondant accents if you wanted.
If you want to do the whole thing in fondant I would recommend using ganache under the fondant rather than buttercream.