Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:5334120.
I made this minor mod for the awesome and versatile picture frame system by Geeky Faye Art, available here: https://geekyfaye.art/digital-shop/
The idea is to print four of those corners and turn your ordiary vertical-wall picture frame into one that can be hung on angled walls or even (if you feel adventurous) the ceiling!
I decided to glue the corners onto the frame instead of screwing them, which is why I decided to ignore the screw holes. Also, keep in mind that this is the metric version. If you need the imperial one you might need to resize this slightly (possibly in your slicer)
All credit, inspiration and coolness go to Allie - they did an amazing job with that picture frame!