This is something I happened across one day, I was attempting to vacuum seal some leftovers, semi-liquid state.
So I freeze in a shallow pan first then into the bag and vacuum away.

As I was placing the sealed bag into the freezer, I see two or three blue (reuseable) ice packs.

The idea hits me, why not make my own...................

I freeze several shallow pans of water, place in the bag, vacuum and done. I left one on the counter to conduct a little test, it thaws and I refreeze, worked like a charm. I make them in exactly the perfect sizes I need to fit lunch pails, cooler, etc.

They travel well and if broken, no yukie blue stuff.

Also, it helps to use up the odd sized bags you have left over that are to small to do anything with.

I have even experimented a little and placed some chucks of foam soaked in water and frozen in a few to use as emergency ice packs at my kids sporting events. They melt and form to the injured area better than just the block of ice.

“Two things are infinite: the universe and human stupidity; and I'm not sure about the universe.”
― Albert Einstein