Yes, the cardboard is a good one, i had this idea befor i have just never acted on it. as my walls are wite, but im planning on getting mylar
BONG0 Reviewed by BONG0 on . Mylar Question Does it have to be completely flat against the wall? i have it taped up and i didnt try and flatten the mylar out, its really loose and moves when the fans blow on it... and now that i think about it, it would probably reflect more light if layed flat against the wall... any opinions on this? Rating: 5