The sides of car #3280 are plain in design and could be fairly uncomplicated to model with layers of styrene.
A B&M mechanical department document indicates each car side of #3280 has 2 door openings that are 8' wide. An enlargement below of the car circled in the opening photo of part 1 shows that this car has 2 sliding wood construction doors per opening.
The above photo also shows this car had reinforcement plates under each door opening, a belt rail and what appears to be a batten strip separating the letterboard area from the lower part of the sides.
It is my understanding that it was standard B&M practice on all converted baggage/express cars that each baggage door had one window large enough for a person to egress in an emergency. The photo below of a B&M converted Pullman clearly shows the one window large enough for that purpose per door, this is the wooden door design that will be used on the model.
Above are the known and photo evidence details of B&M #3280 car sides. What is not known for modeling is the placement of the baggage door openings and any rivet pattern on the car sides. The 20' to center door opening placement in the drawing below is only conjecture but this measurement looks like it could be near to correct and will be used on the model.
Making the Sides
The sides will be modeled with a four layer styrene system used on other rolling stock previously built for the layout. The photo below shows the first 2 layers.
The base/1st layer is .010" thick styrene cut to the length and height dimensions required for the sides. A strip of .060" 1/4 round strip styrene is glued to one end only of each base layer for modeling the car corner posts, an existing vestibule door jamb will frame the opposite ends when mounted to the Branchline core.
The 2nd layer is also .010" thick. This layer covers the base layer and will form the exterior surface of the doors that will be visible on the finished model. All other areas of the base layer will also be covered with .010" filler pieces that will be unseen on the finished model after the 3rd layer is applied over them. A .025" slot will be left open under each door, this will be for a .020" thick door sill to be mounted later.
Below are a sample of the many parts that comprise a door, these are just the vertical pieces that will be used when assembling the doors on the second car side.
Each side sheet has 3 basic parts, the upper side sheet, lower side sheet and a .015 x .060 upper belt rail piece. The .060" wide surface of the upper belt rail piece will be glued sandwiched between the upper and lower sheets, leaving .015" x .020" protruding further out from the side sheets to represent the top of the belt rail.
The .010" thick batten strip and lower belt rail piece are actually parts of the 4th layer of detail. The lower belt rail piece will be glued directly under the upper belt rail piece completing the belt rail and the batten glued were needed.
One of the six completed side sheets is at the top in the below photo.
Below are both finished sides.
Pieces of .040" thick strip styrene fill in between the side sheets above and below each door and .040" 1/4 round strips make up the door jambs to complete the 3rd layer.
The 4th layer door opening reinforcement plates are in place under each door, these are also .010" thick. The door sills will be added later before painting.
The windows openings will be cut out and mounting holes will be drilled for all hand grabs before the sides are attached to the Branchline core.
Not having photographic proof of the rivet pattern on the prototype, a generic rivet pattern was applied with Archer rivet decals.
Next time will finish the car ends and roof.