Here are my three panel-mounted Cable Entry ports. The four mounting holes are 4mm diameter on 30mm center to center spacing. I used PLA 20% infill and a Gyroid infill pattern, although Cubic should work equally well. No supports were necessary using my Ender3 Pro with a bed temp of 60deg and a nozzle of 205deg. The CAD work was done using SolidWorks 2010 and the STL output sliced using Cura. A drop of Cyanoacrylate secures the cable very well. The three prints are defined as follows:

Cable Entry 6mm: As the name implies, this mount accepts a cable with a 6mm outer jacket diameter.

Cable Entry 9mm: Similarly, as the name implies, this mount accepts a cable with a 9mm outer jacket diameter.

Cable Entry: This mount is a simple shrouded cable entry/exit point accepting up to 15mm outer jacket diameter cable or multiple cables of lesser outer diameters.

The photo depicts a 25-conductor cable with a 9mm outer jacket,

I hope you find these as useful as I have