How do you make a simple container that prevents ice from melting?

Answer 1

To stop ice from melting you are going to have to stop heat getting to it so you need to wrap it in a good insulator. Wrapping the ice in bubble wrap or putting it in a box made from polystyrene foam would work well, the thicker the insulator the better! A waterproof insulator is good because water is quite a good conductor of heat, if you say wrapped it in straw then the water released from the first bit of ice would soak into the straw and make it a less good insulator allowing more ice to melt. You could get around this by putting the ice in a plastic bag and wrapping the bag in an insulator that wasn't waterproof. For any container the more ice you have in it at the start the longer some will last. Ice can be kept in a high quality vacuum flask for quite a long time but if you are looking to make it yourself then it would be far from simple.