Under-shelf rod holder (with parametric model)

Simple easy-to-print rod holder for mounting under a shelf. 

Print it laying on its side, no supports needed. 
Feel free to skimp on the infill - the perimeters are more important here. 
I recommend ABS or PETG for a sturdier print, but PLA should be fine for light duty.

Parametric onshape model available here (open the variable table and edit parameters to suit your shelf and rods).