Customizable bicycle chain guard

Its not beautyful, but it does the job.

Define the following:
outer_radius --> Outer Diameter of the guard (How far of the chain should the protection reach
radius_center_to_screw -->radius from the center of the pedals shaft to the screws (pretenting that all screws have the same distance to the center and are equally distanced to each other)
bore_diameter --> make it as big, that the windings of the screws grip, but dont brake the case
distancer --> how high are the screw inlets? this also defines the distance from the chain wheel to the guard. Make it big enough that it does not collide with the chain and small enough that its doesnt touch the arms of the pedals;
number_of_screws --> number of screws (which themselves are equally distanced on the guards plate)
thickness --> thickness of the guard plate