I made a video talking about the benefits of this design: https://youtu.be/RmZ7aJYvWLc 

I did not explain in the video, but I used a Sharpie marker with a very fine point to color the chamber of the print all black. 

This is a technique for getting the PTFE tubing threaded into the M3 nuts: https://youtu.be/LQDa5_xappU?t=25m53s I prefer to ream out the tubing after it is threaded into the nut. This is a necessary step because the act of threading compresses the tubing thus decreasing the ID to the point where it restricts the filament. Ream it out and you are good to go.