To guide a pocket door with no bottom grove in the door.  Sorry photos are of an earlier design I have not printed this design yet.  The new design has screw hole guides and bevel edges to reduce the chance of damage to the door.  The "U" part is also set to go the other way.  

Just printed the new design and there are two small faults.  I will upload the old design and see if I can fix the faults this weekend if I have enough time.