I know my ferrets are spoiled, because they have their own custom heating pad . . . . 1. Make, buy or use an old throw pillow cover with a zipper closure. 2. Using all cotton fabric, sew a pillow to fit the cover. Fill it with enough whole, unprocessed barley to make a good, cushy beanbag type of pillow, and sew securely shut. 3. Microwave the barley bag until comfortably warm (a minute or two for a 12"x12" pillow) but not too hot for the ferrets. Tuck inside the zipper cover, and let your ferrets enjoy! Make sure the barley bag stays dry - the separate cover should be washable, but the barley is not; it can mildew if it gets/stays damp. Don't nuke the cover - zippers can do nasty things to microwaves - and the barley bag needs to be cotton because poly/poly blends tend to melt . . . .I have a few which I use for my arthritis, and I made one for the woozles when they all got the greenies last spring and needed extra warmth. I didn't want to use a water bottle or anything electric, so this was ideal - and they still enjoy sleeping on it. Dry Rice will also work as a filler, but it doesn't hold the heat as long - barley is available at most feed stores. I paid $7.00 for 50 pounds (that's a lot of barley warmers!) Blessings to All Carla & the Woozlemaniacs [Posted in FML issue 1425]