Need cable holders for round cables?
Make any size you like in customizer. Print and just add a nail or screw.
I needed them in black - but they are available in every color of filament :o)

-- Version 2: Fixed countersink bug.

Countersink: Use "Angle" for screw and "Normal" for nails

Print lying down for best flexibility.
I printed 8 in 10 min using no rafts or support on Makerbot Replicator 2 with 10% infill and 0.2 mm layer.