We are thinking of doing something similar after looking at all the options out there. We will cut the reflectix a little larger than the windows, and then cover them with some thin fabric. Then we are planning to sew horizontal seams in them every inch or two so that they can be rolled up a little easier. I want them to be semi-permanently mounted to the windows so that we don't have to store them anywhere. So right now I am thinking I might install a few snaps on the top of each, and then a snap or magnet strap to keep them up when we roll them up. Going to try to avoid velcro though, in Phoenix the adhesive just gets kind of nasty. I'll post pictures when we get this project going. It's on my winter list