Just a simple design you can alter using the Z Height in your slicer to make it any length you want. You can also adjust the Y axis to allow for more cables inside.

I just used some VHB tape to secure, but you could use other materials to fix to whatever surface you want.

The size is about an inch overall with about 20mm inside as is.

I used TPU for mine for the flexibility of putting the cables inside and also 'stuffing' them in.

I have a bunch of them.

The one image shows a few short runs (6" I think) on the back of my TV right under the LEDs near the top and there are other vertical ones that aren't really shown.

Crappy photo, sorry.

Simple and 'flexible'.

Print however you think works best for you since it is purely functional.