If you're going to D.I.Y., here are a couple images of mine from before I tossed it. There wasn't anything complicated about the sheet metal, other than the folds that the glass ran over. I'd suggest mocking it up out of cardboard forst, like when you made paper boxes waaay back in your high school geometry class ...
(It was so long ago for me that we had to use clay tablets. That was kinda hard. You hadda fold 'em before they fired the clay in the kiln.)