After replacing my lock cylinder, it protruded just under 4mm too far on the outside.
This disturbed me visually.
The cover I found on Thingiverse (https://www.thingiverse.com/thing:5419804) unfortunately did not fit the outer dimensions.
So I measured the lock cylinder and the door fitting and designed a cover in OpenSCAD.
Printed with transparent PETG at a layer thickness of 0.2mm.
The author hasn't provided the model origin yet.