Its vibrations, we thought, were akin to t’sounds of a saw when Mitka t’Little Finger plays it singinn t’aria of a sleepinn cuckoo.
An ordinary handsaw, held between the knees, bent into an S with one hand and bowed along the smooth edge with the other; bending it further raises the pitch.
How it is held

CC BY-SA 3.0 · Sägenprofi · Wikimedia Commons · licence
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And what it sounds like
Natalia Paruz playing the Ave Maria attributed to Caccini, on her own channel.