I'm about to start the production of my first grow box. I would like to use mylar, as it's known to be the best material to use to line your box with, but I can't even begin to find a place that carries it, or knows where to find it. But I've seen in a few threads where people have used the reflectors meant to be placed in a car windshield to reflect away sunlight. Now my question is; Do these actually do a fairly decent job at reflecting light? And if so, is it comparable to flat white paint, which I believe reflects around 85% of light.