I am thinking that there are places that make business out of acquiring industrial and commercial surplus for the sake of resale. And it would be a place like this that’s prop department might visit for supplies. Is that about right?
They literally got extra parts straight from a plastics factory. These were current, or at least recent, production parts (probably about to be trashed or melted down). I know there's a book or article that mentioned this. Maybe the making of ESB or some interview with Frank Bruton, prop master.
If there's a lot of a particular part, they likely came straight from the manufacturer (Michell, the plastics factory, RS components, etc).
Sometimes there's off-the-shelf stuff that they bought multiples from a store (boy scout supplies, exactra calculators, tape recorders, V8 kits).
There was obviously a bunch of aircraft scrap, army surplus, camera equipment too but there is so much of it that was current.
If this orange thing is part of a product (like a car) it was likely manufactured in 1981. If it's a product (pipe fitting, conduit, whatever) it was likely on shelves in '81 or recently discontinued/clearanced.
The newly found boot studs... those were definitely brand new at the time. They may all have been from a single pair of boots bought by the costume department. There might be a background alien in ROTJ wearing a pair of Hunter boots.
