These are files to go with a measurement microphone construction article I posted last year at https://www.diyaudio.com/community/threads/a-diy-mems-measurement-microphone.417231/ It's a lot of instruction and discussion, so you'd best go read about it there if interested. The article also provides links for PC board design, parts list, etc.
The critical part is a little resin printed holder for a tiny Knowles MEMS microphone chip (SPH1878LR5H-C), to provide a way to mount it with very small cross-section to on-axis audio waves. This is important to provide repeatable frequency response flatness (within 3dB from below 10Hz to well above 50kHz). Other stl files here are for a mount for the metal tube (using a stainless steel drinking straw) to fit on a standard microphone stand or boom to minimized wave reflections; and for an electronics interface/equalization box to provide power and to flatten a resonance peak of the MEMs chip.
I will soon be posting stl files for another version of this microphone that decreases the noise floor by about 9dB, getting its noise performance adequate for recording studio use.
The author marked this model as their own original creation.