Don't know if this has been posted here already, but I saw this on Facebook and figured I'd share. Looks like a great, economical idea to me:
Homemade Flexible Ice Packs
Mix 1 part rubbing alcohol and 3 parts water in a ziploc bag and seal, squeezing out all air possible. When frozen, the pack gets ice cold but remains flexible to contour to injuries.
Some prefer 1 part liquid dish soap and 3 to 5 parts water. However, most who use this agree that the cooling qualities of the ice are far better transferred through the alcohol-water mixture than through the soap and water mixture.
Put some gauze 4x4s in the ziplock before adding water and you'll have something a bit more formed, yet still very flexible. Good for keeping cold on larger areas, say.. a high check ligament that needs cold wrapped around and the length of the injured area.
I found that the alcohol disolved the plastic bag, and made my freezer a mess. Also the leaking bags would sting if the skin on the leg was broken. I now make soft ice packs with 1/4 cup salt to 3 cups water. You may need to add or subtract salt depending on how cold your freezer is. Add blue food color so you know what's in the bag.