DIY blower door test?
This page describes how to build a DIY blower door:
Basically you use a furnace blower and a cheap magnetic or tube-of-water manometer. You can’t finely tune the speed of the blower like a professional blower door, but given the few built-in speeds of the motor, you can generally find a speed that yields close enough to 50Pa that you can extrapolate the CFM50.
I have a furnace fan already sitting around from my decommissioned oil furnace, and I just bought a Dwyer Magnahelic manometer on Ebay for $15. Is this crazy or should it really work as described?