I'm making a three tier superhero birthday cake.  On the top layer, the customer would like a Hulk fist coming out of the top.  I'm wondering if I should do it in RKT or carve it out of cake.  Also, should I cover it in fondant or modeling chocolate?  Which would be less heavy?  Thanks.

I think it would be easier in rice krispies and then cover it in two layer of fondant. This should really help you :) http://www.kamicakes.com/blog/hulk-smash/

Thanks! Great instructions. How much in advance can I make it? I don't need the cake until February 26.