Your Neje kit installation should look something like this…
and the following video has installation instructions starting at about the 8:00 minute mark…
An alternative if you have the Neje 30W or 40W laser head with the amber/red window is my air-assist nozzle design seen in action here…
You would print the appropriate nozzle (the 30W and 40W versions are slightly different) from here and replace the amber/red window on the laser module with the printed part. Plug in the end of your air hose from your kit. Use the valve (and coupler if needed) and hose… you wouldn’t need the metal needle or small printed bracket pieces.
– David