Video doorbells aren't much use to someone who can't see.
The new BorgCo device addresses this problem.
The caller places their chin on the chin-rest of the outside unit. A passive infra-red sensor detects the face and activates the device.
A laser scans their face, and the indoor unit chimes, then using an array of solenoid-driven pins deforms a sheet of thin latex to exactly mimic the contours of the caller's face.
By running their hands over the latex, the blind person can feel the shape of the caller's face, and thus recognize them.-- 8th of 7, Oct 28 2017 Invisible Ninja Sculptures for the Blind Invisible_20Ninja_2...20for_20the_20BlindA more upmarket approach. [Wrongfellow, Oct 28 2017] How do they find the unit if they are blind? ha-- xenzag, Oct 28 2017 The indoor unit makes a noise.-- 8th of 7, Oct 28 2017 "Oh my god - Pinhead is at the front door!"-- MaxwellBuchanan, Oct 28 2017 You'll wonder why you hesitated ....-- 8th of 7, Oct 28 2017 Good try but I’m not into that particular flavor of polygamy yet, although if you were to tweak your intake process so that your demographics reflect a little more energy from the community of chicks who are both hot and also Asian, then I would probably consider focusing more attention on what you are saying.-- JesusHChrist, Oct 28 2017 I suspect that even [8th] has higher standards, [JHC].-- MaxwellBuchanan, Oct 28 2017 Sounds like a job for a highly trained ninja sculptor! [link]-- Wrongfellow, Oct 28 2017 Not to spoil the party but reconstruction from two pictures would be cheaper and less prone to getting needled in one's eyes.-- Voice, Oct 30 2017 random, halfbakery