In the music industry it is common to distinguish between equipment that is designed to be used on stage and (sometimes or) in the studio. Equipment, such as microphones, going up on stage tends to have two features in common, not prone to induce feedback and mechanically robust.
For this build I would have to cnc machine some parts, I don't think I'm able to get the precision with a hand cranked milling machine. The tricky part will be the membrane, or diaphragm. I have to design it such that it and the coil assembly is flexible enough to transduce sound in to a signal. In addition the coil have to be light (Newton's 2d law of motion), at the same time have a healthy ration of number of turn and impedance.
Edit, I actually have two knock off Shure SM58 microphones (the sound is sort of good enough for rehearsal studio). You're first post inspired me to look for replacement capsules for these microphones. But ss you said, they come with a hefty price tag, but swapping seems to be done in minutes.