I am making a Barbie doll cake with a ruffle dress..... Would you use fondant or gum paste for the ruffles??

I originally thought fondant but then maybe the gum paste will hold better?? Any tips would be appreciated.

Fondant is fine, or modelling chocolate if it's not too hot where you are.  By the time you've rolled and frilled each ruffle, they are pretty dry anyway so don't need much to help them hold.  If you do find them sagging, you can pop some kitchen roll in between to hold them 'til they dry completely.

A∆∆∆ What she said. And, if doesn't want to stay as poofy as you need it to, you can add a sprinkle of Tylose to firm it up, but not so much that it becomes gum paste. 1/2 tsp. per pound maybe.

Thanks for the advise ladies! Worked a treat!!