We've done it! After a long period of R&D we have produced a covert under door camera product that is effective, easy to use and with a price tag that is far more attractive than it's market equivalents.
https://rvasynergies.co.uk/security-inspection/securuty-cameras/47-under-door-camera
Read the full article here http://www.watson-marlow.com/ie-en/news/oem1/