I made these rails and clips to run a cable along the ceiling.  It is a fairly light duty system which is probably best used for up to 2-3 cables.  The space within the clip is about 15mm x 24mm.  Each segment is 15mm long and the tracks are segmented so that the clips can be spaced evenly.

The light duty clips snap on to the rail easily but don't provide significant resistance to side forces.  A clip support piece can be slid over the clips at the end to lock them in and take up the side forces the ends of the track might see.

All parts can be printed without supports.