The subject says it all. How do I store a buttercream cake with a figure made out of RKT and covered in fondant? Right now I have it in a big sealed Tupperware bin, but I am afraid of the fondant sweating or something like that? Help me! I have to deliver this tomorrow! Thanks all!

I wouldn't keep it in an airtight container. Either open the lid slightly or move it to its box and leave the top ajar. You want air to be able to circulate.

Yes, it is being wrapped in between each use and I tried to work with it to smooth but this only occures when the color is in it and it is set asside. I know the colors are good and as I said it is not this way when I pull a piece from the block that I am using only after it is mixed with the fondant? so strange and weird, idk :/

Do not store the cake in an airtight container. I put mine into the cake box with the lid taped to hold it up off of the figure. Then I tape plastic wrap to cover the open space. I have never had a problem with my cake or any of the figures doing it this way.