Putting fondant drapes on a cake is actually pretty easy. the hard part is getting the folds on the
fondant even if that's the look that you're going for.
Of course, you can just fold the fondant over to make the swags, and have them be more irregular like most fabric hangs naturally.
But for a more formal look, using dowels can give you the more regular structure that you want.
Here's a video to show you how to do it, or you can just read the description below: http://www.youtube.com/watch?v=re9UpQyfrEM
Take a few dowels and roll out a piece of fondant the length of the swag that you want. I used a pasta roller to the fourth thickness for this one. You can add a little tylose to the fondant to make it firmer if you have trouble rolling it out without ripping it, or use a 50/50 gumpaste/fondant mixture.
Put the flat piece of fondant on the dowels and press it gently so that the fondant lies flat between them.
Push the dowels closer together to create deeper creases in the fondant.
Get the cake ready to place the drape on it, either by adding some water or sugar glue to the fondant surface, or by piping some buttercream on a buttercream cake in the position the drape will be. If you're doing this on buttercream it helps to have it cold so that the icing is firm when you place the drapes on it.
Pick the fondant up off of the dowels, starting at one end and holding the folds gently together to keep the shape of the folds.
Place the drape on the cake and arrange the folds so that they fall evenly on the cake. If you want to make a drape that looks fuller, add another piece of draping next to the first one. This cake had two sections on each drape.
Kara Buntin owns A Cake To Remember LLC, online cake supplies at www.acaketoremember.com and www.acaketoremember.etsy.com