Aluminum tape works well.
You saw how I used it on my DIY lighting thread.
Here is a post from that thread
www.myfishtank.net/forum/417253-post50.html
If you were going the route of ridgid metal, aluminum roof sheeting might be your best bet.
You would need to use some regular steel wool to polish/clean the metal.
After that, polish/wipe it off and it'll shine.
Maybe to attach it you should look into some sort of construction adhesive.
You will need a drill and/or tin snips.
Make the holes you need then mount the ballasts on the inside of the hood, inside the DIY reflector.
I'm assuming the ballasts have mounting brackets.
Make sure you drill or cut out venting on the top of the hood and also near the bottom.
The problem with having high heat and only top venting is a lack of air circulation.
You need low vents to allow cool air to be sucked into the hood while the hot air rises.
If not you'll create an oven.
Your other safe bet is to install a CPU cooling fan.
The bulbs are long and narrow this is good for space saving.
I am assuming the sockets are mountable to the hood as well?
These are going to have to be mounted to the top or the back.
Unfortunately the plastic hood is going to have to be drilled and bolted through.
I suggest that you attempt to do all of the mounting on the back of the hood.
This way it'll save the front/top from any unsightly hardware.
Once you get all the components needed, the installation should be easier than DIY lighting w/ screw in CF.
The crappiest part of DIY w/ CF is figuring out how to mount the sockets.