Just noticed that the microphones that I hand built come in a kit now. The main "over the strings" mics that I use are basically:
https://www.jlielectronics.com/diy-microphone-kits/endora-microphone-kit/
And the ambisonic array mics I use are XY pairs of:
https://www.jlielectronics.com/diy-microphone-kits/samantha-microphone-kit/
Buying as a kit raises the price considerably - I made 4 of the Samantha mics for probably about $150 in parts, and my pair of Endora's maybe cost me $250 for both. But they're definitely worth the money as they are the equivalent to much more expensive commercial mics.