I agree with previous comments - nice modeling, great write-up and excellent illustrative photos. I have a few of the Westerfield 36' Canadian Fowlers and one D&RGW Fowler to build, so this will help me, too.
A couple of divergent practices from your model building approach that I use. On Westerfield boxcars with the built-up roof trusses, I make a sub-roof of .030" styrene that is the same width as the floor, but perhaps 1/8" shorter, score it down the center, and bend it on the scored line. I use the Westerfield formers to determine the 'slope' or dihedral of the roof halves, and use CA to cement them at 4-5 locations on the bottom of the sub-roof. The resin roof halves are cemented to the top of the sub-roof with contact cement, and centered side-to-side and end-to-end. The sub-roof assembly should be a drop-fit onto the carbody once the sides and ends are attached to the floor. When everything lines up OK, I add CA around the edges of the roof at the top of the sides and ends.
The other technique is using vinyl spackling compound as a filler for gaps such as the one on your D&RGW Fowler. (The brand I use is DAP Patch'N'Paint Lightweight Spackling.) I use a small screwdriver blade or Xacto #11 blade to apply it to holes, cracks and gaps. It dries withing 15 minutes, can be chiseled, scraped or sanded easily, does not shrink (!!), accepts any modeling paint I've used and has a long shelf life (3-4 years). My first adventure with it was filling holes inside Bowser PRR H21/H22 sawtooth hopper bays where the hopper door parts attach to the outside of the bays. Filling the holes made it possible to run the H21s empty without embarrassment!
From: "Eric Hansmann eric@... [STMFC]"
To: STMFC YahooGroup ; "1914to1940RRingr@..." <1914to1940RRing@...>; resinfreightcars@...; proto-layouts@...
Sent: Friday, December 9, 2016 10:03 AM
Subject: [STMFC] Fowler box car kits
The kit-building bug bit me recently so an HO scale Westerfield 36-foot Fowler box car was pulled from the pile and built. I kept rolling with another kit build of a similar car. Two more box cars are now ready to use! Check out the tips, techniques, and details on my DesignBuildOp blog.
El Paso, TX