[minipci1321]

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.

[belzebalex]

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.

[minipci1321]

I only quickly checked and found this:

https://rusneb.ru/catalog/000224_000128_0000488231_19751015_...

-- click on "Skachat' PDF" (second from the top on the left). Unfortunately it is in Russian, not sure whether English translation exists.

This patent seems only for (X,Y) coordinate capture, but the same authors later worked on 3D setups as well.

EDIT: let me know if you need help with translation

[belzebalex]

I definitely would like an English translation. Though, from what I understand (the diagram and the translation of the title) it's a graphic input device that can work out a few points at the time, and not in the same sphere (as echos will overlap, a point I develop in my article).

So it's not properly able to scan an object like I did?

Apart from that, how have you found that untranslated 1975 Russian patent? Google Scholar?

It's impressive what they were able to build with such low-tech.

[minipci1321]

Replied to your personal address.