This is basically the same handle as the original design,
All I did was to enlarge the hole to make the M4 connector to screw in and the center hole to allow the PTFE tube to pass through.
The purpose was to be able to take the tube right to the start of the teeth that grips the filament and to get a good alignment i made the hole a bit tight so you might need to file it a bit to get the tube in.
I made this as part of the enclosure im building. I wanted a comfortable way to load the filament without handling the extruder it self.
You basically pushes the filament all the way in the lower tube and than just "Extrude" about
4-5 cm, the way you normally would (octopi, LCD or whatever) until it come on the other end. Than you can either push it manually or continue to extrude until it reaches the nozzle.
(Note that im using the "Flexible" extruder top handle with also includes this pointy tip that guides the filament right in... I dont know how will it work with the stock to handle.