Get a plastic/rubber tub with interior dimensions 2 inches larger than you want to have for the inside of your ice chest. Make sure that the chest has a lid that fits it well. If there are handles on your tub, inspect the handles to see if there are holes. Inspect the rest of the tub for holes as well, and seal all holes with duct tape.
Cut 2-inch thick Styrofoam from sheets, bought at a craft store or home improvement store, to the dimensions of the interior walls of the tub. Cut another sheet to fit into the bottom of the tub. Use a low-temperature glue gun and glue to seal any cracks between the Styrofoam sheets and any small holes in the foam. Wait for the glue to harden.
Remove the Styrofoam from the tub. Wrap the outside of the foam with a space blanket, the same way that you would wrap a present. Make sure that the shiny side is facing out. Cut the space blanket where it comes up over the lip of the box and tape it to the foam in this location. Line the inside of the foam box with the space blanket as well, with the shiny side facing out, but again, do not let it go up over the lip of the box.
Place the foam box back into the plastic or rubber tub. Measure and cut a piece of Styrofoam that fits snugly into the top of the Styrofoam box. Glue the Styrofoam to the inside of the lid of the tub using a little bit of craft glue. Before the craft glue dries, put the lid on the cooler (in the closed position) so that the glue dries with the lid pressed against the Styrofoam.
When the glue is dry, gently pull off the lid. Trim the sides of the foam a little at a time until it fits a little more loosely (about a millimeter to spare) on all edges. Removing the lid one more time, add low temperature craft glue to the edges of the Styrofoam in the lid so that the connection will be more permanent, squirting the glue as far back into the space between the lid and the Styrofoam as the glue will go. When the glue cools, check one more time for fit and shave off any foam for a proper fit, as needed. Your ice chest is done.
Things You Will Need
- Plastic/rubber tub with lid
- Duct tape
- Space blanket
- Low-temperature glue gun and glue
- Craft glue
- Add the food first, then the ice, when filling an ice chest so that you do not have to force the food into the cooler. If the ice melts, the water ensures better contact with the (waterproof) food containers to ensure that it stays cold, but it also helps the ice to melt faster. Tip the cooler to drain it as often as you wish. You may wish to add a drain hole by melting one with a soldering iron (in a well-ventilated location), and use an eraser to block the hole when you don't wish it to leak. Foam spray adhesive can be used to adhere the space blanket to the foam and the foam to itself, but it costs more than low-temperature glue sticks.