Each shower rod end has one recessed screw hole in the center.   There is usually a stud near the edge of a fiberglass one piece shower unit.  At 100% the .stl files are O.D. 35.5mm  and the I.D. is 25.5mm.  I'll include the .f3d for editing.  no more shower rod falling down.  My kids abused this for a couple years.. no problems yet.  I printed in PLA, silver.. can't even see any delamination.