I made one
There were some how-to instructions on this out there new once upon a time.
Here's what I recall... approximate....
Obtain a 2x8, about 3' long.
Find and mark center of the windshield.
make a cardstock template of the windshield curvature ... PERPENDICULAR to the windshield at the lower part of the windshield.
Mark center on the template. The template can be a bit longer than half of the windshield. Easier to make in two parts.
Transfer the arc on the template to your 2x8 lumber.
Cut with bandsaw the 2x8, giving you a male and female mold.
Use non hard aluminum, such as 1100.
Determine how much to cut to fit the cowling curve, and cut until lower edge matches that curve
Clamp the aluminum into the 2x8. Not it has a curve that matches the windshield.
Using a roller bend tool, start rolling the flare into the aluminum... zero flare at the side, more flare in the middle.
Make the parts at least twice learning the process!
Thinner aluminum will be less frustrating.