You can also make your own gumpaste by adding "Tylose" (also called "CMC powder") to fondant. This will give your fondant the consistency of gumpaste so you can roll it out thinner and it will harden much faster. I might recommend buying a pack of Wilton brand fondant from Michael's (it's not much in the taste department but it'll likely be stiffer than what you would get by making it yourself). To that note, depending on how many ruffles you have to make, I believe they also sell small tubs of gumpaste, so you could save yourself a step by just getting what you need (gumpaste).
To get (and keep) that ruffle effect until the gumpaste dries, I'd drape them over something (could be as simple as a paper fan made with cardstock) or even lay out some markers/pens spaced a 1/2" apart and place your ruffle over them so they don't droop (does that make sense? I can picture it but it's hard to explain...). Definitely make sure they're totally dry before adding to your cake.
