As I explained the formaly soldering work to hold the strap didn´t do it. The first two pictures show the results before it broke down.
I had a piece of aluminium with two holes in a matching distance to fix it by working - anyhow I had to cancel this idea.
Next I tool a good and strong piece of brass that came to me as I´m a printer. It´s nearly 5 mm thick and thats matching to my plan to screw everything with M3 screws of brass. I made the lenght to fit over 4 of the holes marked in the picture - the outer to screw through the inner as space for the springs. Now I gave them a nice outfit with a file and marked the positions for the thread M3 through the outer wholes of the cupholder.
The briddle in the middle (I know that´s wrong) is made the same way. Of corse I could screw anywere I wanted. The space between the glasses was easy to find. As you know I wanted the glasses to point straight forward, That is why I made a stencil first. I just had to lay the cupholders on a board on my workbench and place my face upon. When I came up I had the perfect distance for me. I marked this on the breadboard with a pencil and a little mark on the cupholder and was able to find the same position anytimes (even without using my face) and had a stencil for more filework.