This is the very first thing i made with openscad. There are things I wish to add but I am still in learning stage so these are it for now.

Thing features: able to change width, height, thickness and screw hole size of your bracket. A sample z bracket with thickness of 3mm, width of 20mm, bracket arm height of 30mm, depth of 5mm and a screw hole of 3mm is uploaded as sample.