is that the stuff that comes in sheets? semi-hard?
The shit works great, its r-matt at lowes, I use it to make walls, instead of using plywwood, or sheet rock works great i plainted them white so they blend in with the walls, I'm sure you could make a great box, onlu thing you might need to put some bracing to to hold the lights or anything else that is to heavy, but that stuff is suprisingly strong, very good stuff and alot lot lighter than and easier to wrk with than wood, all u need is box cutter, some glue, foil tape, maybe some paint you will be straight