More pictures from my other phone - sorry!
The refrigerator vent has a sharp edged hole; clearly, running electrical wire over a sharp edge is a bad plan.
The first picture shows the raw materials: Some automobile fuel line, one 1/2" EMT elbow, and some silicone spray. I cut the elbow in half, which gave me about the right angle to start down the fridge vent.
The second picture shows the ends of the wire/hose/tubing assemblies as they head down the vent.
The final picture is the completed combiner box - except for the final exterior coat of silver paint.
"Between what matters and what seems to matter, how should the world we know judge wisely?" - E.C. Bentley, Trent's Last Case