To the window used transparencies or other transparent plastic sheets. approximately 16mm high and 89mm or 32mm long, two of each. Place these according to the picture, glue on the roof, this keeps windows into place.
The gates may at this scale be a little hard to get good. a standard nozel with a diameter of 0.4 did not work well for me. However it got better with the 0.3mm nozel.
Wheel axle mounting, depending on which wheels are used.
The wheels of the axle is pressed lightly in the wheel axle holder,
You should try things out.
I have used 2mm silver steel shafts. but you can use what you have at
home in the junk box. As long as the diameter is around 2 mm.
The wheels are printed with 0.1mm layer and low speed
If needed, To get a smooth run on the wheels, i turned it lightly on the wheel surface.
it is also possible to put a wheel on a drill and a file smooth surface.