Here is my stator dxf file for JF clone: https://www.dropbox.com/s/b2dzufrzabjpo0m/StatorV3.dxf?dl=0
I don't mind sharing my designs as long as people don't use them for commercial purposes.
I don't stretch the diaphragm that much anymore. For the last few pairs that I made, I stretched the diaphragm only until it's just enough to give good stability. I had to do and redo again about 4-5 times before I got them just right. It's not an easy job. In the future, I will try to make a small table and use the weights to tension the diaphragm. If I can get it right, then making the next pair would be very easy.
You've got everything right. But you might have missed that you need 2 pieces of spacer per 1 driver. You use one piece to glue that to the diaphragm. It doesn't matter that you use copper side or the other side to glue it to the diaphragm. In fact you'll be using the other piece of the spacer to hook up your bias voltage and to transfer the bias voltage to the diaphragm. So when you put everything together, it'll be stator+spacer+diaphragm+spacer+stator....
Your headphones look very well made. How thick is your diaphragm and where do you buy it from? How do you mask the copper on your diaphragm and how do you etch it?
Seeing your pictures making me want to build them too.
I'm not so sure about my coating. On my Omega clone headphones, the last coating I put on them was at least 2 years ago, and the phones still charged up and played very well without any problem. However, all my other phones have been having some imbalance problem. So, I had to take them apart to check the solder joints and recoat the diaphragms from time to time.