I include the OpenSCAD for this model so it can be adapted to other wire spacing or roll diameters, etc. Less easy to adapt if you wire shell has wires running across instead of along the shelf.

It uses an old piece of conduit I had laying around to run through the center of the roll. I has a donut shaped channel on either side for running a small cable tie around one wire to secure it in place (it was easier than I thought it would be to run the cable tie, just need something to push up on the end of the tie as it comes through and direct it through the outlet hole).