Dancer found this in a book called "Sneaky Uses for Everyday Things." It is a way to make those nice sport injury gel packs with having the pay the big prices for them.
Take freezer bag and put in it 1 1/2 cups water and 1/2 cup rubbing alcohol. Put the bag in the freezer for three hours and you have a slushy ice pack. The water will freeze but the alcohol will keep it from freezing solid. Ours was in the freezer overnight, it was firm, but broke apart easily. By being slushy, it fits over whatever you are trying to ice instead of being a rock hard block. Be sure to wrap the pack in a thin towel when using it so you don't get frost bite on the area you are icing.
Being a headache sufferer, I am going to make some smaller ones and sew a soft cover for them. Now I use those hard packs that go in coolers wrapped in a wet washcloth, it never stays where I want it to or only a part of the pack touches when the pain is.