This is a remix of the Extruder Cooling from Thing:187380. The original thing doesn't fit the Simple when the XL Upgrade Kit is installed. For some reason MeshLab didn't swallow my partial scaling of the original thing so I made my own mesh using the original as a template as it is a proven design. This extruder cooling will only fit with a 40x40 fan no deeper than 10mm. According to the information on the page of the original thing It should work on all Simple ordered earlier than October 2013.TOOL: M3 HSS twist drill threaded bit Exact Thread. HSSG Cutting tap drill bit set Exact Thread type M3. INSTRUCTIONS: I sliced it with Slic3r 1.0.0RC2 and printed with layer thickness 0.2 mm. Thread the holes. I do it in two steps, first with the combined drill and thread tap and then with a regular cutting tap.