Shelf Pins by ccmake on Thingiverse: https://www.thingiverse.com/thing:5412753

Summary:
Here are different designs of shelves pins. The diameter of the pins are 6mm and should fit all standard shelves pin holes. I myself don't like plastic shelf pins and prefer to use metal ones, but these can be useful anyway. I would print it at 100% infill for strength. This object was made in Tinkercad. Edit it onlinehttps://www.tinkercad.com/things/fUVnr5pTtjL