2) Check for fit. I rescaled this but, if it is too tight here is a good manufacturing tip. Heat the metal threaded Hot End. This one is an aluminum fitting. Heat with a small torch, soldering iron, lighter or ? Not, too hot but warm enough to soften your screw on cap. Then gently and as straight as you can begin to screw on the cap. Re-heat, adjust and screw as required untill it is seated. I had about 3 threads left at the bottom but, since this is not really high precision your parts may vary.
3) Open the bowden tube opening for a 4mm OD tube. I used a 3 or 3.5mm drill. By waiting until the fitting is screwed into place it is easy to drill out the plastic to fit a 4mm O.D. PTFE tube (bowden tube).
4)Slip an 8mm nut onto your bowden tube then push the bowden tube into your new clamp. Slide the nut down and with some force screw it onto the top clamping keeping the nut square to your Hot End.
I started with this and then saw that jamesarm97 did what I was going to do next - so you can see the other variation on ---- Thingiverse ---- Just search for it - ;-)