With Uschi Elastic Rigging Thread it was simple. I made two springs from brass wire 0,3mm(reinforced by some CA glue) and connect them with the Uschi’s rigging (I used fine size (0,3mm) of the rigging, but now It seems to me that standard size (0,5mm) could be more appropriate.
I still have doubts about how wires should be connected to the central spring. On some examples (my case) I see that they are all going to the spring (small and big V). In some examples I saw that they are connected like W (only wing wires are going through the spring when fuselage wires are straight connected to wings wires) ???