This bracket is to attach a 8mm round shaft end-on against a flat surface. It clamps onto the rod and can be screwed into a support surface with M3 hardware. The SCAD file is included to adapt for any shaft size, dimensions etc.
My print came out within 0.1 mm of the right diameter, so it was already a tight fit on the rod and I was able to clamp it securely with the M3 screw and nut.