My parents have this mirror for years, I believe it's from IKEA. There are multiple segments held in the corners between a plastic part attached to a wall with a screw, and a snap-in cover. One of the covers got lost so I modeled and printed a replacement. This was a rather tough job in OpenSCAD, given the original part was rounded and smoothed from every possible direction, but in the end I managed that well enough, so it's distinguishable from the rest of original parts only on closer look. Printed from Prusament PETG black.