2040 Extrusion cable keeper

I would have thought something like this would already be here on Thingiverse (and it probably is, but couldn't find it).

This is a cable-keeper for 2040 aluminum extrusion. Use a 4mm twist-in T-nut in the non used track. Keeps the cable(s) in the other track from falling out.

I made these for my laser engraver. I'll upload an in-use picture later today.