These new snap pins are meant to address the deficiencies of my previous pin library. These are much easier to insert, more tolerant of different printer calibrations, and stick better to the build platform.
You can include this library in your OpenSCAD designs, or use customizer to export pins and holes for use with other programs.
UPDATE: I added thin fins to the holes, which create slits when differenced. These fool slicers into making webs that strengthen the conical end of the hole. They greatly improve strength for vertically-oriented holes, and can be turned off in other situations if desired.
You can make either free or fixed holes, to allow rotation or not. I always recommend greasing the pins (I use white lithium grease, but I'm sure almost anything would work). It makes them easier to insert and remove, and allows them to turn much more freely without squeaking.
The only part of these pins that are meant to fit tightly are the ends of the snaps. Since these parts are flexible, they work with different printer tolerances. All rigid parts of the pins are significantly smaller than the holes, ensuring ease of insertion.