If you're hosting or attending an outdoor event where there won't be a portable freezer, you may end up needing a way to prevent your ice cubes from melting so your guests can enjoy cold drinks and you can keep foods frozen or refrigerated until they're ready to be cooked or eaten. There are numerous materials that keep ice cubes from melting, but some are more effective than others.
Styrofoam containers are excellent for preventing ice cubes from melting if you're outdoors. The insulating properties of styrofoam inhibit the transfer of heat, meaning that warm air from the outside won't be able to penetrate into the container very quickly, so that your ice cubes will not melt for an extended period of time. The thicker the container and the denser the styrofoam, the more effective insulation it will provide.
Thick fabrics, such as felt and drapery, will also help keep ice cubes from melting because they ward off the transfer of heat. Even though felt is normally considered warm, and it may be counterintuitive to think of it as a good way to stop ice from melting, it is thick, which helps keep heat out and the coldness that emanates from the ice cubes in. If you're using this type of material, wrap the ice container tightly to prevent air from getting through.
Wrapping your ice cube container in thick bundles of newspaper will also prevent the ice from melting if you need to transfer it from one freezer to another. Newspapers offer an economical and practical way to create a reasonably airtight bundle for moving ice from one place to another.
Like drapery and felt, wool is very thick and doesn't allow for much air to pass through its fibres. This acts as an insulator, and will keep the interior temperature constant for an extended period of time. Wool also retards the conduction of heat energy in addition to providing insulation, giving you an extra line of defence against room-temperature air seeping in and melting the ice.