I'm sure there are molds etc that will give you the striped look but I would 1st try using a piece of corrigated cardboard. There are some available in 'card stock' areas of an art store such as Michael's or Hobby Lobby.
Just press your cut 'leaf' of fondant on the board. You can do both sides or just one.
I used a fake seashell for this. I could have embossed it better for more defined lines, but look around, you might have something laying around the house.
Get a silicone cupcake liner or a giant one for bigger folds, you can press gumpaste into that really hard and get a good pleated texture. http://www.zulily.com/p/set-of-4-x-large-muffin-cups-45212-3935845.html?g=1&tid=googpla_Home_Tabletop_3935845_zcvp2&gclid=CLmZ25_N2rcCFcdX3godigkAPA