[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.
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.
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
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.