I had to bend aluminum U channel to make the windshield frame for my project car and it had to curve in both directions. I was using 3/4" x 3/4" x 1/8" wall channel since I needed a 1/2" inside measurement for the rubber U channel that holds the glass. I cut long strips of 1/4" hardboard 5/8" wide and pushed 2 of them into the channed to keep it from collapsing. I have a ring roller I made and it put flat wheels in it to make the part. Gradual rollong in both directions gave me the curvature I needed in both directions in about an hour. Prying the spacers out was a little difficult but it left me with a groove that was just slightly under 1/2".
Windshield 034.jpg
Windshield 035.jpg
Windshield 037.jpg
Ring Roller 009.jpg