Customizable Fan Grill

This is a fan grill for various square fan sizes. This is particularly useful if you can't buy a grill for your uncommon fan size.

The attached stl's are rendered with the ellipse profile. They should be correct in size, but I've only tested the 140mm one.

Note that this doesn't work with thingiverse/Makerbot Customizer. Please use OpenSCAD's Customizer.

Customizer settings:
1. Ring height / thickness / spacing
- parameters for the circular elements

2. Spoke height / thickness
- parameters for the spokes
- large spokes seem to cause more turbulence

3. Spoke generations
- e.g. [1,2,4,8,16]:
- after the 1st ring, create 4x2⁰ spokes
- after the 2nd ring, create 4x2¹ spokes
- after the 4th ring, create 4x2² spokes ...

3. Profile
- cross sectional shape of the rings and spokes

4. Size
- the size of the fan grill = screw hole distance + 2 x screw-hole radius + 2 x screw-hole flange
- for screw hole distance, either measure or refer to https://en.wikipedia.org/