It may be a bit difficult to see in this next photo, but I laid out the marks for cutting the two body side panels. I only had 0.040" styrene sheet on hand, but I would have liked to have used 0.030" thick styrene, because that is close to a scale 2 inches thick, which is what I am guessing the panels are made out of. The top of the side panels measures 40'4". Most of the measurements I just guessed at and deduced from looking at the diagram mentioned at the top of the article and from studying photos.
Careful cutting and snapping gave me the two side panels.
Again, using the above-mentioned diagram, I determined the locations and spacings of the distinctive braces. I used 1x6 strips and glued them to the appropriate locations, making sure to keep them perpendicular to the top and bottom of the side panel. Note that not all spacings are the same, as per the prototype!
After the glue set, I cut and filed each of the braces to length. Next, I glued 1x3 strips on top of the 1x6 braces, perpendicular to the 1x6. The challenge here is to keep them straight and glue them in the center of the 1x6. While the glue is drying on the first one, I am working on the second side panel in this next photo. The weights are there to hold the side panel steady as I am applying the strips.
If you look closely at the prototype, you will notice that the braces actually get slightly thinner near the bottom and the top. The slope near the top is long and therefore shallower. The slope near the bottom is shorter. I marked off how far I wanted to file them, and then carefully removed the material with the file, constantly checking to make sure they all look alike and have approximately the same slope.
Gluing the sides to the outside of the frame was easy once I marked off the center on both the frame and the side panels. A pair of small clamps held the side panels in position while I applied the glue. Now it is starting to look like a hopper! Note that the side panels' bottoms match up with the bottom of the frame. The panels are on the outside, which is clearly visible in prototype photos I found.
The next photo shows the two vertical plates that connect the top portion of the side panels together. They are the width of the frame (9'8") and 3 feet tall.
Using some slightly pressure from the C-clamp, I held the piece in place and applied glue. This was kind of a delicate operation, balancing it all, but it brings the car together nicely.
With some trial-and-error I cut and installed the sloped plates on the ends of the car. They wound up being the width of the frame (9'8") and 7'4" long. I filed some small notches into their bottoms so that they would fit better around the frame. It also helps, since I was using 0.040" thick styrene sheet, to file down the back, top edge a bit for a better fit against the vertical plate.
The corner "posts" were made up out of 2x4 strips. I first glued a strip on the end of the car (the piece that sticks out on the left side of the photo), which partially rests on the top of the frame. I then cut a small 2x4 filler piece that goes against the side sill of the frame. Finally, I glued a full-length piece of 2x4 to the side panel, which covers the small filler piece. That last piece was just glued when I took the photo. I used the pair of curved tweezers to put slight pressure on it to hold it down against the car. This needs to be done to all four corners of the car. When the glue has set, I cut and filed the corner posts to match the top and bottom of the car.
On two of the (opposite) corners/sides of the car a 2"x"4 was attached (with a small filler piece; I haven't quite figured out how the prototype did this). This will eventually be used for attaching grab irons.
I then glued a 1"x4" strip on top of the end sills, against the corner posts. A 1"x4" strip was then glued to the back of that strip and up to the body. This, too, will be used to install grab irons later on.
Two strips of 4" square angles were glued under the sloped sheets. Two issues here: there should have been a vertical panel installed over the bolsters up to the sloped sheet (which would have shortened the angle pieces); and the position of the brake parts on the other side of the car interfered with the placement of the angles on that side (not shown in the photo). Both issues will need to be revisited when I build the next model.
I glued two sets of 4" square angle brackets to the back of the horizontal strip and the under side of the sloped sheet. This was actually a lot more difficult than it looks. I wound up using Aleene's Tacky Glue to hold the bottom of the angle piece to the car, while I used normal Testors glue to glue the top of the strip. Accurately spacing the two strips closely to each other was a challenge. I then fabricated a gussett plate for each of them from 1"x12" strip styrene. I might try making this sub-assembly separate from the car first the next time around.