Drafting Pen body end cap for those rather fine pens with the red ring..

RotRing pen body end cap. Should do as a replacement when the original rolls under the piano and you cant be bothered shifting it to get the thing back.

You may need to experiment a bit with the thread in FreeCad and in your printer settings to get it to match the "real" thread on the body, which appears to be M10 * .75

I produced this mainly to learn a bit more about FreeCad, so I was pleasantly surprised that it actually fits my RotRing Isograph.

Note: This is not an exact copy as