This is a 3D printed version of the Printrbot Direct-Drive Aluminum Extruder.
The design files are posted by the PrintrBot team here:
I had to import the "Alu Expolded.dae" from the above link into Google Sketchup, and save the individual parts as .stl files. I also used netfabb to rotate the top arm, so its easily printable on my Simple.
Last weekend I assembled the 2014 version of the Printrbot Simple with the ALU extruder and was impressed with the results. These parts were printed using the same printer.
I also own a factory assembled 2013 version of the PB Simple, with the Wooden Extruder. I have had some issues with it off and on, over the past few months. The Wooden Extruder has too many parts. This one has been designed well and I'm pretty happy with it.
I plan to replace the Wooden Extruder on my 2013 Simple with these 3D printed parts of the ALU Extruder and see how well it performs.
The STL files extracted from the original design are attached.
The other parts used:
1.5" 6-32 screw
6-32 hex nut
16mm M5 screw