What you want, is something like this:
Black & White Poly It's the best stuff their is. I can buy it by the foot at a store near me, so if you can't find any in your area, let me know, and I can get you some. Tinfoil conducts electricity, therefore, I wouldn't recomend it, as you're gonna have hydro, and water near there. Mirrors require frequent cleaning, and also attracks dust. This poly is, in my opinion, the best thing on the market. It's thinck, and easy to work with, it's also very easy to clean. It costs only about $1.50/foot (CDN $$). One foot wide opens up to about 6 feet tall!
Let me know if you need any further help, as this is my SPECIALTY!!
Check out my indoor garden (this was about 6 months ago)
My indoor Garden