I just discovered the zip lock vacuum bags they come in the quart (maybe larger too) or perfect for keeping my left over fondant pieces and gumpaste fresh. Wrap it in plastic wrap drop it in the bag zip it shut and suck out the air!!
For smaller amounts I put them in fold fold top sandwich bags and tie a knot.. Works great.
Since I have it anyway, I use my FoodSaver. Saves fondant and gumpaste nicely.