Fan grill (Customizer)

This thing inspired by 120mm Fan grill - RepRap style by capitaenz.
I made it a symmetric and customizable.

Customizable parameters are:

• External dimension and mounting holes distance.
• Mounting holes shape and size (cylindrical or for conic head screw)
• Number of "rings" in grill.
• Wide of "rings" and rods.
• Shape of "rings" (true ring or tear drop).
• "Rings" smooth or segmented.
• Central "ring" solid or has hole.

All .stl examples are for 120 mm fan.