Metal Brake on Amazon.
I'm guessing this is too light duty for .040 at 4 feet wide?
What if i went down to .036?
Amazon.com: Malco MB48A 48-inch Portable Brake: Home Improvement
Malco MB48A 48-inch Portable Brake
Bends up to 135 degrees in 22 gauge galvanized sheet metal
Bends metal roofing components and roof flashing including copper and aluminum
Bends narrow roof-flashing strips
Ideal for fabricating plenums or large transitions at the job site
Makes compact fabrications as small as a 4-inch square
Accommodates sheet metal up to 4 feet wide
Adjustable strengthening ribs