Tested: fully working
Mine version of a light direct extruder for Prusa i3 R2.
Here you can download stl files and a step file which contain the complete extruder 3D model. I can send original Creo Parametric files if you want, just keep in mind that I'm using the 3.0 Academic version, so these files can't be opened using a commercial version.
1x 12V DC 40x40x20mm radial fan (see image uploaded)
1x 12V DC 50mm radial fan (see image uploaded)
1x 12V DC 30mm fan
1x Hotend J-Head allmetal and its support
4x ϕ5x2mm neodymium magnets
1x Japan Nidec Copal DC12V Stepper Gear Motor Full Metal Gearbox Ratio 36: 1 (see image uploaded)
3x 625-Z bearings
1x 304 Stainless Steel Capillary Tube OD 5mm x 3mm ID
1x MK8 Drive Gear for 1.75mm filament
1x teflon tube for 1.75mm filament
STEPPER MOTOR WIRING:
Brown - White
Orange - Yellow