For the scrap load, I built a styrene tub using 0.040" as the base, and 0.020 x 0.188" as the sides. If you use the Evergreen tiled styrene, it makes creating the base a snap. 0.25" square tubing was used under the tub to set the right height in the car. I painted the tub with Testors Model Master Panzer gray from a spray can.
The scrap itself is aluminum chips from a plate saw, bonded in place with dilute white glue like any ballast or other scenery material. I drybrushed it with rust, then gave it a wash of a flat black/rust mixture to tone it down.
The billet loads are 0.080" square styrene, cut to about 50' long, which is the equivilent to a 7" square billet, about 6000 lbs each. I glued them together with 0.015" x 0.030" spacers between each bar. I then painted them with Testors Model Master Acyrl Panzer Schwartzgrau. While the paint was still wet, I gave them a coat of a custom chalk mix for that scaly look. (gray, black, blue). The chalk was given another coat of the Panzer Schwartzgrau. When all was dry, I drybrushed some streaks of SAL orange to represent fresh rust. I also painted the ends of the billets SAL orange, as those are fresh cut ends, and would rust quite quickly.
The THING is a generic cracker, pressure vessel, reaction chamber, what have you. I wasn't following any particular prototype when I built it. It was just one of those fun projects to do. The body is from an Athearn 62' tank car, with various Plastruct tubes, nozzles, manway covers, and reducers. It was one of those projects that was quite fun to do.
That, in a long winded explination, is how I built those loads. Now you know the rest of the story.