A clip-on attachment to 1515 extrusion (tested w/Openbeam) that has a channel for routing cables, and secures any cables in the extrusion channel to the extrusion.
Use zip ties or dowels on the two sets of outer holes to keep cables in. Securing the clip with a screw to the extrusion isn't needed in normal operation, but is there for anyone who really wants to.
CC0 1.0 Universal