Customizable Cable Clip
I was surprised that I couldn't find a cable clip that looked like this one on Thingiverse. You can adjust the size to your liking.
The 20mm version is the generic cable clip size.
For the latest version of this design, please refer to its github page
https://github.com/adgaudio/3dPrinter/blob/master/random_parts/cable_clip.scad