This is my first and smallest 3d printed bowl feeder. You get both the .stl files for printing as well as the SolidWorks files for modification. You can see a video of it running with M3 hex nuts here: https://www.youtube.com/watch?v=xXfcDdvP9jU

I print all my bowl feeders in ABS plastic as I find it gives excellent wear characteristics. I finished the prints by sanding the working surfaces smooth and then wiping them down with acetone on a rag. This will significantly lower the force needed to make parts feed.

This is a very basic design - if you intend to use a 3d printed bowl feeder for more than experimenting I recommend that you consider my MKII or MKIII bowl feeder instead which are more mature technologies.