Sometimes repetitive stress injuries flare up, or your doc may prescribe ice for your arthritis. Here are some home-made cold packs. Be careful about using these against your bare skin. My physical therapist recommended putting a kitchen towel between my skin and the icepack. And don't keep it on too long: 15 minutes max. You probably won't be able to last 15 minutes, though!
(1) Designate a bag of frozen vegetables for your cold pack. Whack them on the floor to separate the little pieces and then put the veggie bag on your arm (or wherever it's hurting). I find this much better than a leaky bag of crushed ice. The veggies conform to the contours of the arm and give greater contact, and thus greater relief. I refreeze for use again. Since it's not recommended to eat these frozen- unfrozen-frozen-again-etc. peas, I mark the bag.
(2) Pour 1 c rubbing alcohol and 2 c water in a quart-sized zipper bag. Squeeze out air and seal. Place this bag, zipper down, in another quart zipper bag, again squeezing out the air before sealing the second bag. Freeze. Mixture will be a slush (because alcohol won't freeze) and thus very "mold-able." Refreeze after use. This recipe can be doubled; use gallon zipper bags.
Label this! Rubbing alcohol is poisonous! As security: tint the mixture with food coloring in a non-food color, such as blue.
(3) My physical therapist gave me this one. Fill a Styrofoam coffee cup (the 8 oz. size) with water, almost to the top. Freeze. Peel off the cup, leaving 1" so you don't freeze your fingers.