A little while ago I rediscovered a small bag full of components for a microphone. A high quality large diaphragm condenser insert, 1 GR resistor(!) and a FET amongst other parts. The plan was to build them into the rather nice casing for a USB condenser microphone. I never got round to it, but I just was cleaning out my bookmarks and found this:
https://www.audioimprov.com/AudioImprov/Mics/Entries/2017/5/7_Schoctava%2C_a_simple_mic_circuit.html
Watch this space!