When I'm going to be out and about for hours, I don't always do this but I like to pack Canaan a juice box and me a Dr. Pepper or water to drink so I don't get tempted to stop & buy drinks for us. I put them in an insulated lunch bag with an ice pack. I've found that lunch bag ice packs are either too thin or too bulky. The ones that are too thin don't keep much cold for very long.
So improvise a soft gel pack to keep a lunch or drinks cool or use it to soothe aches and booboos. Reuse them until someone pokes a hole in them or dispose of them because it's easy. I personally don't like the rice filled bags because they don't get cold enough.
Now it's true, this may not be worth your time and effort but again it gives the kids something else to make that's actually usable and works well.
Here are some recipes that I've found that work well.
For lunches & drinks:
1. Use 2 good quality Ziploc bags. In the first bag, mix 1 part rubbing alcohol with 3 parts water. Squeeze all the air out and seal. Put the first bag with the mixture into the second bag. Squeeze all the air out and seal. Now freeze.
2. You could also put this mixture in a rubber glove and seal it well by twisting the end, folding it over and tying a couple of rubber bands a lot of times around it.
For aches & pains:
1. Use 2 good quality Ziploc bags. In the first bag, pour Palmolive dishwasher detergent in and leave 1 to 2 inches from the top. Squeeze the air out and seal. Place the first bag into the second bag, squeeze the air out and seal. Now freeze. This ice pack is perfect for conforming to your body, very pliable and can be used over and over. When you're done using it, reuse the soap for your dishes.
2. You could also put the soap in a rubber glove and seal it well by twisting the end, folding it over and tying a couple of rubber bands a lot of times around it.
3. Buy a cheap bag of frozen peas. Mark it well that it's not to be used for eating. This is also perfect for aches & pains, even headaches.