I got an email from QS saying that he posted a Joule Thief Beeper to his web page, about 2/3 of the way down. I think it might make a metronome if the speed was adjustable. basically it’s a two transistor circuit with a single coil made from the voice coil of an 8 ohm speaker.
I built one of these long ago, and used a 9V battery and small 2 inch speaker. The circuit worked for a while, then failed. The voice coil went open, possibly from excessive current, or else the voice coil vibrated itself to failure. With a supply voltage of 1.5V, there should be no problem with excessive current.