continued with the PJ :
taped the lines and covered the areas with small dabs of maskol (using a synthetic sponge with large holes, not the blister type sponges)
Some minor issues encountered, the worst being me : I wrongfuly painted the whole rear inner wall of the garage white. Instead of coorecting I'm thinking a mural (advertising something related to the automotive industry) would be nice, but I don't know wether I'll manage that (being new to airbrushing and sucking at freehand drawing..)
anyway, some pics of the not yet assembled pieces :
one issue was the masking tape tearing stuff from the model (the paper, some cardboard strips I glued on and some maskol) :
Also : too much maskol creates too large spots of worn paints or spots whose contours are too well defined. I already touched these up as you can see in the next pic :