Summary

This is Airtripper's Bowden Extruder Modified to hold a push fit connector.

Instructions

The units I purchased were less than $3.
MC KQ2S04-M5 PBT Push-To-Connect Tube Fitting, Hexagon Socket Head Adapter, 4 mm Tube OD x M5x0.8 Male

These push fits and other 3D printing accessories available here as well:
http://www.tridprinting.com/Hot-Ends/#3D-Printer-Push-Fit-Fitting