I've fiddled around with drawing up similar things (fan grills) in autocad at my school, but haven't actually made one. We have CNC machines literally in the same room as the CAD machines, so I imagine that it wouldn't be all that hard to throw it into GibsCAM and machine something similar out. That is if I knew how to use GibsCAM =P.
But for most use I imagine Sketchup or even photoshop or paint would work. You'd just need a steady hand for the last 2 =3. Then just print it out, put it on the material you will use to make your grill and cut away.