Kitchen Shelf Peg (another option)

I modified this model with Blender just to clean up the geometry and change the proportions to match my kitchen-peg system which was a few mm different than the original Thingiverse model. I also filled in the "bottom triangle support" completely rather than use the 1-3 supports. (You can see the difference in the photo comparing the original and my print.) Finally, I adjusted the size of the peg for my kitchen cupboard holes and tapered the peg slightly. -- It worked great, first time!

I would strongly encourage you to measure your system (ideally with a calliper for high precision), and adjust the model precisely in all of the dimensions.