Heh, I've been cooking up a very similar plan. I have two reptiglo cfls in a diy fixture. Now it needs a reflector which I planned to make out of galv flashing just like you.
You beat me to the same basic idea, but mine would cost a little less. Someone could use regular aluminum flashing, polish it the best they can, give it a spray of a clear lacquer so it doesn't tarnish and remains more reflective.
After having been accused of badmouthing CFLs without having tried them I did something slightly similar. I used a light bar that is 26 1/2 inches long. I had two old 19" bat-wing reflectors so I overlapped them so they were 30 inches long and attached them at the bottom of each side with a tiny sheet metal screw.
But I wanted more reflection and from lower than the bat-wing light hoods would give. I used regular flashing, I used a drill with a buffing wheel and some polish and got what shine I could, and as even as I could, shaped them so when each matching piece was attached to the bat-wing hoods, with the lights lowered as low as they could go on a seedling the added on pieces were outside of the pots and almost to the floor.
I put four 'Y' connecters in the four sockets in the light bar and in them put eight 26W, 6500K CFLs. I was only testing it on four plants so I could space the plants so each plant had on pair of bulbs in a 'Y' shape directly above them.
I didn't veg to a tall height, and I was only trying the CFLs for vegging, and almost until their final vegging height most of the plants had the home made reflector side additions close to them. I figured it would reflect more than my flat white painted walls would that were over a foot away in any direction, given that CFL light rays are so limited in intensity/distance/depth etc, would.
After having done that I thought for someone who is really low on bucks but would want to do something along those lines, or even make their own reflector, if they could get some of the sheet metal from a discarded water heater they could do the same thing for free, plus having the option of picking the white painted side of the sheet metal to use to reflect or polish and lacquer the other side and use it.
Either a makeshift reflector or any home made reflector won't compare to a high quality professionally made one, but if one of those is someone's best or only option so they can grow and do as well as they can lighting-wise, then I guess they do it.
. I think I will be lazy and not bother with the foil, just use the shiny side of the galv flashing.
