As titled, this is a cover for a 40x40mm fan.
Screw holes are M3 counterbore. (Easily modifiable in SolidWorks, 2014 or later.)
For an idea of what it could look like printed, this should give you an idea (http://www.thingiverse.com/thing:879619)
Fan_Cover.SLDPRT | 1.0MB | |
Fan_Cover.STL | 1.3MB |