I've seen some of the older posts about R2D2 cakes but none have covered how to apply the fondant to the cylindar 'body' of the robot.

I'm planning to make four 8" or 6" rounds for the body, which I'm guessing will make the cake too tall to cover with fondant the usual way (lay fondant over the top of the cylindar and smooth it down and all around-- I'm assuming the piece will have to be so big I won't be able to move it over and onto the cake without it tearing or drooping and getting uneven in terms of thickness). So, I'm thining I've got to somehow wrap the cake with the fondant around the outside-- make a big rectangle then wrap it around the outside of the cylindar?.= how do I do this so the fondant doesn't slide down and sag. Better to have a lot of buttercream around the outside of the cake first, or is a thinner layer better?

Any tips for applying fondant vertically, on the sides of a cake?

I had the same dilemma when I did my R2D2 cake. I did not use a lot of BC underneath either. What I did was measured around his body and his height. Then rolled out my fondant an inch longer than his measurements. With my cake his head was separate so I was able to fondant him vertically and leave that extra inch or so over the top of his body. And his head sat on top of that. I had no problems of fondant slipping at all. Also he was in the fridge every moment (besides decorating) until he was served. I have a picture on here too. I hope that helps!

Here you go, hope it helps

http://www.easy-cake-ideas.com/star-wars-birthday-cake-2.html