A moebius ring, after a few trials, this is what worked for me : shell 2mm infill 20% Support ( cura ) overhang angle : 50° Printed at 70mm/s .2mm resolution.

I tried no infill, forget about it, you'll waste plastic ;) 1.2mm shell was too thin in some spots where the angle is very low.

How to design this in blender : https://www.youtube.com/watch?v=s6Jqb4dIV9g