DIY Microphone from a Motor
This design turned out to be the most successful, and quite a few experiments were conducted.
I tried firmly securing the other end of the diaphragm or adding weight to it, but the results were less successful.
A thin protective glass from a smartphone also worked well as a diaphragm, but it made a noticeable ringing sound, worse than what was heard in the video.
Many words are difficult to understand, because subtitles have been manually added to the video; you can enable them in the settings.