Use the steel brush to add grain lengthwise in the planks.
Then stain the wood with a mix of india ink and brown pastel chalks mixed with water and some alcohol.
When dry, rub once more with the steel brush to get rid of standing wood fibre.

With one brush, wet one plank with turpentine.
Then with a flat brush, paint with acrylic color.
I used white here.
Work the paint lengthwise on the wet turpentine. Continue until desired effect is reached.
Use the glass fibre brush to add extra weathering if wanted.

I use the same technique on the laser cut windows.

I then glue the planks onto the sub walls.

Then I cut off the overhang and add the windows and trim.