Remix of http://www.thingiverse.com/thing:1173355
Now has a ducted fan and mount for Johann's retractable z probe (its what the 3 holes are for). I'm using reflective silver tape on the bottom of the effector to keep it cool for when I get a heatbed. Hotend bracket is to fit a jhead from hotends.com The effector takes a 5015 squirrel cage type fan.
The arm spacing is 52mm. FreeCAD file is included so you can edit it if you need to.