We got a shelf for my son’s room and it has sharp, metal corners on 2 sides. This model is meant to sit on top of the edge where the corners of the front and side walls meet, to provide a little protection against bumping into the corners.

This was designed to rest on top of the corner and it's not a tight fit—so it can be removed later on without leaving a mark. You can add some putty or adhesive to keep this in place.

As far as print settings go, this was a quick print that used my P1P’s default settings for PLA—without supports. The infill was bumped to 25% for a little extra strength, but the model should still print fine at ~15%.