Home Depot Week: Foil-Backed Tape
Okay, the possibilities for light mods here are pretty much endless. Ringlight internals, beauty dishes, custom macro reflectors -- go nuts. The stuff is pretty cheap, too, depending on how big your project is.
HD has is by the 30' x 1.89" roll for $2.27. Or you can get it here, too. (Scroll down.)
I am curious to see what ideas you might have in store for this. Hit us in the comments.