Two seasons ago, I built a mirror
blind. I used four acrylic mirrors that cost $600.
Used it one time, in shallow water that had NO cover, but the pintails were in it thick.
More trouble than it's worth. Wind is a real problem. Open top was a real problem (sprig dropping in from 200yards up would NOT finish). Finding it again after moving the boat was a real problem. The sun was a real problem.
It's a cool idea, and I may yet still modify the thing and try it again sometime.
Those pictures of the Mylar blind show a blind that is very easy to distinquish. If the camera were placed 20 yards in the air, like a duck would be, the blind might blend in better.
Often wrong, never in doubt...