I am making a First Communion cake with fondant chalices on the side. I am using a petal pan so the chalice will have to be curved to fit the pan. I would like to make them a week before but how do I keep the fondant soft enough so that when I put it on the side it will conform to the side of the cake? Will it stay soft enough in a sealed container or will it still harden? I just don't want to do all of the work and then have be to hard and crack or try to soften them just a little by putting them in the microwave and then ruin them that way. I haven't worked much in fondant except for doing some figures. I did them a week ahead and they were very hard by the time I put them on the cake, which was fine with me. I didn't put them in a sealed container though, just a lightly covered. Would that make the difference?

I would recommend drying the fondant pieceson the sides of the cake pan. THat way, they will conform to the curves and it will make it much easier to place tem on the cake. Just make sure you dust the pan well with cornstarch or powdered sugar so the chalices don't stick to it.