Something you can actually always use, a cable duct. This one is 30 millimeters wide (outside) and 26 millimeters wide on the inside.

The cap can be attached to the lower part using a simple click fastener and removed again if necessary.

You can adjust the size individually, simply change the dimensions in the slicer and remember to do this for the top and bottom parts.

I hope you can use something like this, if so, have fun with it!