I bought a used AT2020, but part of the mount was missing.

This mount has a 3/8" thread, and you will need a M6 bolt + nut to fasten the mount. I also needed to remodel the collar which fastens the bottom of the microphone, which is included here.

The spacing for the screw is 3 mm.

Probably usable for other microphone mounts as well. I might update this model with a washer.