I recently came across this RBOX photo by Colin Reinhart. I liked the white paint-out across the bottom portion of the boxcar, and the white spray painted reporting mark, and thought I could maybe try to do something like this with one of my RBOX's.

The number of panels/ribs is different than the prototype photo, but the colouring of the car is about right from my previous weathering of it. As a first step, I painted black overtop of that red primer that I had on the door.
I made this styrene mask to help soften the upper edge of the white paint patches. The styrene spacers, which I've outlined in black here just so you could see them, fit in between the boxcar ribs and raise the edge just a bit off of the model. Flat white for the paint.
In this view, I've sprayed the flat white on the right side of the model, and it's taped in place on the left. Also the door is masked so as to not get white paint on the black 'cuz that wouldn't be good
Some looks at the finished project...
I used a white paint pen and some patience to try to sort of emulate the similar scribbled marks on the prototype picture.
The graffiti is decals by Blair Line. The reporting marks are decals from the Microscale Stencil Lettering set.
A look from the B-end.