To make soldering easier, the plug needs to be made. 2 discs were cut, and spacers were glued inbetween.

Than i realised, that i can not wrap the cardboard round it. Cardboard was spliting, even when it was soaked in water. Plan B was, to cut 8 discs, each 2mm thick, and glue them to form the plug.

1mm wire was wraped round the top, and secured with strips of Tamiya tape. First soldered joint for testing. I used Koki paste, and Dremel soldering iron with fine tip.
I removed the wire from the plug for strength test, and it is very strong.

So i started again. I used two different wires. The 0,7mm for top rail, and 3 stantions, and the rest is 0,4mm.