Fan Grid Multi Holes Generator

Sometimes, during the design of a device, you have to add one or more cooling fans.
Because the fans should be able to blow air to / from the external environment, you need to drill holes on the surface of the case that you are going to draw.
There are normally two options:
1- Drill a trivial circular hole of diameter slightly less than that of the fan impeller, providing the necessary lateral holes to hook a protection grid
2- Drill a set of many, small holes or slits (for the passage of air) directly on the body of the case, thus avoiding having to create the holes to mount the protective grid, and the use of the grid itself.
Of course, both for reasons of cost and assembly, the 2nd solution is often preferable.
The following OpenSCAD script allows you to generate just the "negative" of these holes / slits.
It constructs a series of parametric solid objects, which can then be used to "pierce" the surface of the case you are going to design.
For more details an