Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:6310397.

This is a slight alteration of the lockable pegboard rivet by rharding13, with an internal filet and a flat side to orient to the print bed for increased strength to prevent bending between layer lines. I found that it was far too easy to snap the rivet legs when inserting due to the weaker orientation of the layer lines at the bend stress point. This reorientation should alleviate that problem and be far more resilient. The rivets use a small piece of standard 1.75 filament to lock them once inserted into the pegboard.