re: Frozen Ice Palace and Mountain CAKE

Hi, your cakes are amazing. I am on a steep learning curve at the moment but I would love to make this cake for my daughter’s birthday in February. I get the mountain and I know you have said the palace is part cake part RKT, but what do you use to cover it to get such detail? I’m sorry I’m sure its obvious but any information you could give on what you have used or how you have sculpted it would be hugely appreciated. Thank you.