Can be used to cover ventilation holes in cabinets as well.Features a recessed vane area so the blades don't hit the grille. You can set the number of vanes, number of circles and all sizes including vane and circle thickness and center circle thickness.The included STL is for a standard 60mm fan with 4 vanes.For others, open the SCAD file and set up the parameters for your fan. They're pretty self explanatory.The side towards the print bed is the outside (away from the fan).Instructions: print, use.