4mm PTFE tube fitting replacement for Titan Extruder

[Update May 25 2017] My original print broke off due to weak layer adhesion and can not stand up to constant retraction. To make it strong, print it sideway and in the slicer program lower it so that you will have some surface area on print surface. (You don't need it to be perfect circle anyway) Also, I scaled it by 98% so that the screw is tight. Depend on your filament and your extrusion rate, you may have to experiment a bit to find the right fit.

This printed part with the tube fitting d