Thanks! I'll make a trip to home depot tomorrow. Any idea if will cut it to size for me there? Probably won't be able to fit a 4'x8' in my car. The other option is just to take a hand saw and cut it in the parking lot

Awesome. Thanks for the quick reply figjam. A couple clarifications:
* Any difficulty in cutting the stuff?
* The plastic corner molding is just to make it possible to attach the boards together?
* What's goop?

To everyone making the box coolers: what are you using for a box? I can't find anything big enough with horizontal sides at any hardware stores nearby.

To those that are building a box, what materials did you make it out of? And how did you ensure it was waterproof / airtight?