I saw this someplace a while back and thought that could be a neat idea. So I tried it.
The balloons stayed nice and frozen, especially on bottom, until the next morning.
I know you are curious. If you are having a party and you want to ice down some drinks. Make frozen water balloons. Now you can't use those little dinky water balloons balloons. You need to use regular sized balloons.
I know you know how to make water balloons but here goes. Attach to the faucet.
Add water. (It's hard to take pictures while adding water to a balloon)
Tie it and place in a plastic container. The container helps keep the balloons until they freeze.
Ready for the freezer.
On party day, put a layer on the bottom of your container.
Add some drinks.
Layer the drinks and balloons. I have to say they kept the cold drinks cold and the balloons on bottom were still frozen solid at the end of the party. Not mess. So give it a try.