I used some Reflexi-whatever in my van. It cuts easy with a box blade and I taped it up with what is essentially duct tape (but it said 'super strength' or something on the roll. <br><br>I also used some foam board over my windows and it's worth noting that within a few weeks (maybe four tops) the boards were warped and bowed significantly more than when you purchase them. Also, we used a lot of this foam board when I worked in framing and fine art and 'old' foam board (the basic kind you get at craft/office stores, yes) degrades horrible - especially in heat. It flakes and crumbles and falls apart. After these two experiences I wouldn't use it, personally.