I see tons of recipes for ganaches, but they must have to be different when using to decorate 3D cakes? I need one for coating RKT deer antlers and head, for a smooth, firm surface before covering with fondant or modeling chocolate.  The antlers may just be foil wrapped aluminum wire, then ganache, then MC.  The head will definitely be RKT.

Can anyone please give me some guidance? Thanks!

If you are covering wire for the antlers, why would you use ganache and then modeling chocolate?  Just use modeling chocolate.  Same for the rkt deer head. The modeling chocolate layer will smooth the rkts.  No need for a middle step with the ganache.   BTW - I just use melted chocolate on rkts to smooth. I don't mess with modeling chocolate for smoothing.  It's more work and more ingredients if all you are doing is smoothing out the bumps and not actually "modeling" something. 

These are covered with modeling chocolate from the beginning, and even molded with it.

http://sugarsweetcakesandtreats.blogspot.com/2010/08/barney-and-friends-cake.html

http://sugarsweetcakesandtreats.blogspot.com/2010/11/toy-story-cake-and-cupcakes.html

There are different ratios for ganache that you can use to make it thicker. Art and Appetite has a good explanation.

http://sugarsweetcakesandtreats.blogspot.com/2010/05/covering-cake-in-ganache.html

http://www.artandappetite.com/?s=ganache

When I did my deer horns, I made them out of RCT then covered them in melted chocolate....painted it on with a pastry brush.  Then I covered the horns in fondant.  

Ha! Thanks, imagenthatnj! I'm using your MC recipe ;)

I guess I thought the ganache would make the MC layer smoother--but maybe I'm just too used to fondant and needing a completely smooth base :)  I am covering the antler wire structure with **foil**, so it will not be as smooth as even RKT--I thought filling it with a little ganache first would reduce the amount of MC, squishing and hand-smoothing. No?

ddaigle--these antlers will be a full set and mounted, so I'm afraid they'd be way too heavy and fall over if I did them out of RKT and then fondant. (LOVE your nickname :))