Two questions. First, if I covered it in fondant (the body), would I cover it horizontally or vertically? Horizontally seems easier, but would I run the risk of it sliding off in the heat outside? Vertically seems like a nightmare to smooth out!

Second, how do you cut the body of the cake since it is essentially one big stacked cake?

For me, easiest to make the body would be to stack two 6" round cakes and a 6" half ball cake (wilton sports ball pan). This should give you pretty exact the body shape and about 36 servings, no carving needed. All modeling would be made with fondant.

As for covering the cake - I would stack the two round cakes and cover them together horizontally (strip around the cake) with overlap on the top of about 1/4 - 1/2" - smooth it over the top, perhaps even set circle of fondant on the top in the space in between to even it out. Cover the half ball cake "normal", from top, leaving overlap on bottom, again smooth it over the bottom. Stack this two parts - R2D2 has a strip pretty exact where the two parts meet and this would cover it.

I find this page helpful - although it is "how to draw R2D2", it will help you to decorate it. I assume the "feet" would be partly cake stand, a construction only covered with fondant/gumpaste/???

^____^ what she said

I tried covering a cylinder vertically. It is nearly IMPOSSIBLE to smooth out on a 6" round cylinder. Think of covering a glue stick with a piece of tissue paper and you can envision it. My result ended up in the cake disasters gallery

Using the technique majka_ze described, that 1/2" fondant overlap will glue the fondant to itself. If your icing crusts, be sure to apply the fondant prior to crusting, or spray the icing to wetten it if it's crusted - you want to make sure the fondant is nicely glued to your icing too.

When I did my stockpot cake, I used 3 6" rounds, torted, so there were 6 layers in total. I separated them into "2 cakes" using a cake board for the top 3 layers - so serving was easy. Basically, you just have a two-tiered cake, only the two tiers are fondanted together. Just make the cake board small enough that it doesn't poke thru your icing of course. (sorry to state the obvious). I doweled the bottom "tier" (i.e bottom 3 layers) too, just to be safe.

Mine was made with 4 8 inch rounds separated into sets of two. I covered mine like any other cake and was just patient in the smoothing and it went fine. I use mmf, dont know if that makes a difference. It was very tall too...about 11 inches with filling. Total height with feet was around 16 inches.

Thanks guys. I will definitely put fondant horizontal, with an overlap on the top.

Ceshell, I love that idea of torting and then putting a cakeboard between them. That will make cutting much easier.

I have to make an R2D2 cake in January and I definitely plan to do the same thing. Good luck with yours!