Pinwheels are pretty optimized from a design standpoint, and are so cheap and easy to build that putting a pinwheel to work as an HVAC duct flow meter seems like a great idea. Great in theory ...

After months of work, the best I could ever hope for ... Don’t put this stuff on an HVAC system. Instead of the cloth-backed “duct tape”, I’m using the stuff you should use on duct work.