Ender 2 (CR-2) Extruder Chamber

A coupler of an extruder and Teflon tube of the Creality CR2 (Ender 2) is made of plastic (female thread) and metal (male thread), respectively.
As expected, frequent installation/reinstallation can cause serious damage the coupler. So, I decided to make a simple extruder for my Ender 2.
A metal union (Fig. 6) with Teflon tube is directly installed into the plastic extruder chamber (Figs. 1-5) without the use of any tools (eg., wrench, screw driver etc) and extra parts. After installing the m