A fan cover I needed for my printer housing. I created it for a fan with 120mm in size and a 5mm heigt of the top part. That way the notches could hold the cover on the fan. It is also easy removeable.
The included gcode is for .2mm layer height. If you want "better" notches, decrease the layer height in total or only for the last 1mm of the model height.
The gcode also includes infill without top and bottom layers. That way a kind of grid is created to let the air through. So do not be confused when the model itself has no holes. The holes are visible in the gcode or slicer file.
The author hasn't provided the model origin yet.