zlacker

>>belzeb+(OP)
Great accomplishment, but people were building 3D ultrasonic scanners back in 80-ies, for much less than $100:

[didn't read your article, your claim has put me off, sorry]

-- use an electric spark gap as the wideband acoustic source

-- use 3 simple electret mikes on 3 axes. Mikes don't need to be high quality (spark intensity can always be raised as necessary), so they were hand-assembled using metallised mylar film (used nowadays to pack some food, or ESD-sensitive electronics components).

The rest was data processing.

>>minipc+SV
Very interesting! Do you have any links for me to learn more?

There are a few limits on what you can scan with only 3 mics. I detail everything in my article. Really suggest you read it.