I sometimes do voice-overs in iMovie and need a more directional mic. This thing easily snaps on the top of an iMac and makes the internal mic more directional. I got this idea from pblanton who needs this for Skype.This was designed for a mid 2010 27" iMac, I don't know if Apple changed the dimension between the cooling slot and the top of the screen on other machines. On this machine it measures roughly 10mm from the top of the cooling slot to the top of the screen, then roughly 28mm across the top.All parts were printed on a TOM with a MK6+. My settings were: Object infill% 35, Layer height(mm) .32, Number of shells 0, feedrate (mm/s) 32, RAFT and FULL support.I requested RepG's Print-O-Matic to add a necessary raft and full support, for some reason it gave me a very sparse support structure and the print turned out rough, but still functional. Any help with this problem would be appreciated. Print the part. Clean up any sharp edges with sandpaper. Place the deflector front down first then push down until the rear tab snaps into rear cooling slot. To remove, just lift the front first and it pops off.