I applaude your project and innovation, However I wonder about the durablity of the coroplast at various angles of attack relative to the airflow.
One alternative is to use an aluminum damper from the HVAC industry.
A quick scan on Ebay I found one for $49.99.
Honeywell ZD18X6 Square Zone Damper 24 Vac 2 Wires 18x6x4 In | eBay
It may not meet your needs but there are many more dampers listed there.
Just a thought, I really like your design and concept so please don't think I am discarding your ideas in any way.