Parametric clip
Blend radius makes a strong print

Make your own in OpenSCAD typical parameters are shown below.

Diameter_to_grip=20;
Number_of_clips=1;
clip_height=12;
width_of_base=34;
depth_of_base=7;
clip_wall_thickness=2;
center_line_distance=36;

I have not put any holes in as I intend to print 100% infill and drill my own for fixing
or just screw in from the back.

OpenScad