1 cup rubbing alcohol
2 cups water
zip lock bags
blue food coloring (optional)
That's it! SO simple, and these are awesome. Do some in gallon bags for more flexibility around knees, etc - use the same amounts given here. When frozen, these feel exactly like the expensive ice pack I paid a lot for, for Matt's knee.
Next I want to sew some covers for these.. we can wrap them in dish towels for now, but covers are nice.