1/8" x 1 aluminum bar stock. To bolt it to the radiator, use some pan head screws and some J-clips. Then you basically just use some additional pan head screws, drill holes through the shroud tabs, and bolt it on with some washers. I'm kind of a nut about this stuff. Most people thought it was some high dollar fan lol
I think others weren't so into trimming stuff like I am and used wider aluminum stock and had it stick out past the edges of the radiator.
