Inspired by @flackenstein's plug.

I wanted a single piece plug. And I wanted step files instead of STL. So I got the calipers out and designed one from scratch in Fusion 360.

This is a new version of my previous design. A comment from @JamesKiely_379170 mentioned a twist open-close function would be nice. So here it is.

Two versions are provided. “no screw” version with integrated center post, and a version that takes an M5 screw from the bottom to hold it in place. I recommend using the M5 screw version if possible.

The Fusion 360 design is parametric, have fun changing variables.