I was looking for a cable holder to attach to the side of my work bench to hold a bunch of smaller cables. I couldn't find one that was exactly what I was looking for so I made my own. It has three screw holes for easy mounting to the surface of your choice and will hold smaller cables (like USB cables) quite nicely.
It is 125mm long with 12 5mm wide slots. The ends have a 4mm raised bit to help keep your cables from sliding off.
I've included my SketchUp file if you would like to modify it to suit your needs.