Make a well-insulated travel cooler

Step 3 Foil facing

Since the cooler is going to sit in the car being irradiated by the mid-day sun, it would be best to reduce the amount of energy being absorbed by giving the cooler a reflective surface. The quickest and cheapest way about doing this is by using an aluminized mylar sheet- AKA space blanket or emergency blanket. This only costs a couple bucks and is about as effective as placing the cooler in the shade. That may not sound like much, but it's a good deal if you can't put it in the shade.

For the sake of durability, the aluminized face should be positioned toward the inside. You can identify the aluminum face of the film by rubbing on it with your finger (the aluminum comes off) or using an ohmmeter.

The mylar is attached to the box using a spray adhesive. I used green label 3M Spra-Ment, although there are several compatible adhesives available. CHECK THE LABEL. Not all spray adhesives are safe on foamboard. Cover the box by rolling the sheet around the sides, leaving the excess to form flaps to cover the top and bottom. If you can wrap a present, you can do this. It's best though, to spray the box (not the film) one side at a time. The glue tackifies quickly, and you can't reposition the film on tackified glue. Once the film is in place, It might be a good idea to use clear packing tape to hold down all the edges and reinforce the corners.