I am trying to make a birthday cake with Elmo and Big Bird coming out of the cake in 3D using RKT. It is going to be on a 12 x 18 sheet cake. I made Elmo last night and even after setting all night the RKT just don't seem to be firm enough to hold up to a coating of "furry" buttercream. (I have his arms extended as if he is saying "surprise"). Is the any medium I can coat the RKT's in to firm them up and then coat with butteercream. Any ideas or suggestions are greatly appreciated.
Homemade or commercial RKT?
Homemade, because the models are pretty large and I didn't want to have to purchase so many boxes of store bought.