It seems hard to think this tiny rig was designed and built so long ago (1974?). It was rebuilt a few years ago and still works. It must count as one of my favourite all-time rigs.
I would not recommend trying to exactly copy it, but use it as a source for your own designs. Some years ago, I know one club did a PCB for a version with a loudspeaker amplifier and loudspeaker. I forget who this was.
In its day it had several 100km QSOs handheld and even one of 160km to France handheld even though just 10mW AM. These days, most local QSOs are on FM. In its day, it was a very small rig and much smaller than commercial handhelds.
When our grandson (14) stays with us he likes to go bell ringing hunting. We tried 2 places today, but both had no bells ringing. He did capture the 10am chimes at one.