I recommend printing everything in either PETG or ABS. PLA can't really take the heat that your new E3D v6 will be putting out. Requires these STLs from Prusa's site, [here](https://www.prusa3d.com/downloads/others/prusai3_mk2s_stl.zip) - extruder-cover.stl - extruder-idler.stl - fan-nozzle.stl Assemble using Prusa's build guide, [here](http://manual.prusa3d.com/Guide/5.+Extruder+Assembly/295). You can then screw the extruder side of your drag chain onto the front of the top set of holes on the extruder body. Finally, you can screw your stock X axis endstop switch with the level pointing downwards onto the front of the left set of holes on the extruder body.