Small Shelf Pin/Peg 3.2mm Fits IKEA Billy Bookcase

I liked grizziel17's model, it's very simple and designed to print without supports. 

Note: this is for a custom cut shelf to fit an IKEA Billy bookcase, it is not meant to be used with IKEA shelves with the round cut-out for the IKEA pins

The IKEA extra shelves are reasonably priced, but I had spare wood, and if you need multiple shelves the savings stack up.

scaled down model until the pin was roughly 3.2mm diameter & extended the pin to 80mm