This thing has been designed in OpenSCAD in order to replace a broken mounting bracket for a kitchen light. I am supplying one example .stl file and the original .scad file, that you can use to adjust the bracket to your needs.

I had the most success in printing in the alignment from the original file.

I didn't find anything similar that could be parametrized by open source software in an easy way. I hope it also helps you :-)