Just print the parts. Use 2pcs M3x10 screws to attach to the motor (left side). Use M3x16 screw for the idler-to-extruder body. The bearing is standard 608 skate bearing. Attach it with M4x10 (Notice that it's M4, not as the original M5!). If you have M4x12 which is more common in my case - use the spacer. For the Idler tension - you can use a M3 screw bigger than 12mm in length! It's a good idea to put a spring there as you have a notch with which you'll be able to change the filament easily!
Use a push-fitting for 6mm OD PTFE tube (4mm ID). I have a Chinese E3D version all-metal extruder and the PTFE tube came with it.
Notice that the screws for holding the Bowden compact extruder to the frame are M4! In the original part - it's M3. When you print with 3mm fila, it's a good idea to hold it steady to the frame. :)
Finally I was able to make everything fit with the 1/8'' brass push-fitting for 6 OD PTFE tube. Everything looks nice - but there is important note that in 1/8'' version - you'll need a 24T gear drive wheel. Like this one: http://www.ebay.com/itm/26T-Tooth-5mm-Bore-Brass-Filament-Drive-Gear-For-DIY-3D-Printer-Extruder-/141353563206?hash=item20e9543446:g:sjoAAOSwEK9TzNeZ
I haven't test it with a hot-end yet... I mount a motor with less torque - if it's working with it, it will work with every motor that has more torque. :) Still waiting for the hot-end to arrive (I hope it will be this week).
I printed it with 0.2mm layer height and 50% infill.