In building this model in styrene, the dimensions of the roof settled length and width questions. Car height could be determined by looking at the car side data. The car doors would need to be shortened a bit, and the photo showed how the car body framing and side sill peeked out below the sheathing. The underframe was an 'early ARA' type, for this 40 ton capacity car. Here is how I modeled it, making a few changes to the Intermountain underframe and putting on brake system and piping details. The car floor is modeled with 1/8" scribed styrene sheet 1/32" thick. A similar sheet is used for the top of the car flooring, with a 1/16" thick strip of wood between them. This makes a car floor close to scale thickness. The three-piece brake parts are from All Nation, molded in black plastic. They are easy to drill for adding the brake piping and rodding. Athearn trucks and Kadee couplers were added.
The body was built in sheet styrene, over which the outer scribed siding was added. The doorways were cut out and the doors made to slide open. This permitted a load of bagged flour to be modeled. Chiclets gum pieces were used, suitably coated to avoid munching by little 6 legged critters. Because the weight of a full load of Chicklets gum could destroy the car, they were only piled up at the doorway and are removable as a unit. Strips of 1"x1"soft foam insulation was cut to fit into the car ends with some pressure to hold the load in place. Some gum pieces were decorated with color pens for a make-believe mill with a blue star emblem and writing. Brown kraft paper for the floor lining and baking powder dust complete the load details. The Viking roof shows well here. The running board and corner platforms are built up with strip wood. The individual grab irons are made with brass rod.
The ends of the Lehigh Valley box car are the basic flat panel, riveted ARA end. However, they are also fitted with re-enforcing ribs, as seen here.
Basically this model is an Intermountain car that Intermountain never made. It's shorter in height, being it is an earlier than 1937 design. The load inside makes this model weigh 16.5 ounces.
Taking this thread a step farther, here is a totally scratch-built car that was inspired by an article to build one in HO from an old Model Railroader magazine.
This model was built in 1987 in wood with styrene overlays for the sides and roof. A stamped metal All Nation box car end was cut down to make the steel ends.
It has a fully detailed underbody. At the time, this WW II era car was not available in O scale as a kit or ready to run.
To get one, you made your own.
It won Best of Show at the NMRA Northeastern Region Convention at Saratoga Springs in 1997.
Fielded by the Rock Island to carry tinplated steel rolls for manufacturing food cans, it carries the prototype's designation to be returned to Pittsburgh PA when empty.
A long stretch from the Rock Island line!