Aluminum foil is a very common mistake
in first time grow rooms. While the foil will
reflect light, it also reflects pockets of heat
as well. This is very dangerous because it
can create these pockets of heat on your
plants in unforeseen ways and can easily
burn your plants. If you want good indoor
coverage, I would suggest looking for white
instead of metal. White will reflect light as
more evenly and efficiently. My person, and
extremely cheap, method right this second
is using white drawer liner. You get them
rolls from the hardware store. They are
for lining the bottom of your kitchen
drawers. They are made of plastic and
will not hold water and rot, and they are
mildly sticky on the back. I duct taped
mine on the inside of my grow box.

But I can assure that poly panda paper
will be the best thing you can get.
Mine is in the mail.

Good luck!