Needs a "how to" description
....unless I've missed it somewhere
How they're made varies, depending on the type of scrap.
For the large lumps I cut up waste Plastruct and plastic tube, bits of old wagon kits, gears etc. I try to avoid wagon wheels, unless they're laid flat, otherwise the thickness and size of the flanges becomes apparent. Sheet Plastikard is also useful. There is a press/baler modelled and the crushed cars are made from aluminum foil, painted and weathered. These also become part of some loads.
The swarf and small scrap is actually the contents of my vacuum cleaner, after vacuuming the shed floor. All sorts of tiny scraps that have escaped the workbench and dog hair! Real swarf, from my lathe, is also added as small scrap.
Everything gets glued to either a card base that is supported so the level comes up off the wagon floor, or those plastic coal loads that come with Airfix 16-ton mineral wagon kits. The entire load is painted with rusty colours and, when the paint is dry, is treated to rust weathering powders. Some parts are picked out with coloured paint as not everything in a scrap load is completely rusty.
The scrapyard is supposedly located in what was at one time a railway goods yard.