My wife had knee surgery last week, she has to keep ice on her knee most of the time due to swelling.
We have 4 drugstore "cold packs" in the freezer that we were cycling through, but they all take too long to get cold, and don't conform well to the knee.
The surgeon told us about this little trick...
Get a bottle of GREEN Palmolive dish soap....he said it has to be the GREEN one, the others won't work.
Pour it into a 1 gallon ZipLock bag (the ones with the actual little zipper preferred)...and put in freezer.
Works amazingly well, gets REAL cold REAL fast...stays cold a long time...it's a kind of light lime green gel slop, and it conforms like a gel.
Give it a try next time you screw a part of yourself up.