[doorgunner69]

Go for the heavy duty oven wrap stuff. the thicker the better.

A few years ago when the start up company I was with was folding up, I interviewed with an outfit developing an ultra-wideband radar that supposedly could detect human presence through walls.

They were trying to sell it to investors as a "baby monitor" sort of thing to make sure you kid's heart was pumping normally, etc etc.

No idea if it ever got off the ground. UWB radar for surveillance through walls has been around for a while.

[MaxMax]

Items like that usually go away. The LCD portable screen was squashed
imo, because it would allow people to wrap their cars in the stuff and
use it to become almost invisible. Or even themselves.

[Gaffer]

It wasn’t for a “baby monitor” it was for a SWAT team pre-entry recce to determine where in a room humans are.