My current version of my aero cap is skinned with Foamular with a wood frame. You might want to try a few designs in in plywood or even Coroplast before embarking in Lexan or acrylic. Acrylic is prone to shattering/fracturing/cracking when stressed or impacted. Lexan can handle impacts to a higher degree. Lexan is more expensive than acrylic. UV light will eventually cloud Lexan or acrylic over time. UV coatings can extend the clarity of Lexan or acrylic.
If you do a lot of stop and go, you may not see a major improvement in yer gas mileage with an aero cap.
