This is a remix of the Open Hardware thumbscrew thing # 121099. I liked the shape and I liked the logo, but I needed a knob and not a thumbscrew, so I decided to import the stl file and remix it in OpenSCAD.

I am using these knobs for the LCD Controller's rotary encoders on my 3D printers. These fit on the 6mm split shafts snugly, you may want to scale the things up by 1 or 2% in your slicing software if they are too tight for your particular application.

I am including my OpenSCAD source as well as the original stl, so the thing can be remixed further.

These knobs can be printed with the open hardware logo up or down, I prefer the result when they are printed with the open hardware logo up.
In my case, in PLA with 35% infill.