I recommend printing the cableholder with this Flexible TPU-Filament http://amzn.to/2pTIli0 , so you have a bit of flexibility which is very useful for different cable-diameters.

I glued it with an Scotch 3M whicht you can get here: http://amzn.to/2oScHS3

I added the*.f3d-file from Fusion 360 if you want to modify the Cableholder in any way.