I was in trouble, because I needed to use white 2length technic connectors to the windows, and doors. But Lego never made it in white color. So I have bought 100 pieces from this:
The item is very rare, and very expensive. I have bought 100 pieces for 30EUR. Nowadays it costs on bricklink 1-2EUR/pcs
So, project is go on.
My plan was, I make black window frames into the doors, but in the earlier model it was not the best choice.
I used this to install the frame, but the centre of this is larger, than any simple technic connector:
There was more friction, and sometimes cannot open the doors, get stucked. Maybe i use doors without black frames :(
Yes, it is very huge :)