Wonderful thoughts and ideas.
I guess the original description does lean heavily toward prefabs. My idea wasn't toward something world-specific (though it could), but more for small things that could be dropped into modules to just add a little something to the feel that it's more real...because not everything in the world is big, powerful, magical, or even considered important to everyone.
I'm really liking some of the model ideas mentioned as possibilities already. For some more inspiration on the model side, here are some examples of what I've done for my PW that would be similar:
- honeycomb placeables for hanging under tree limbs
- small cobra statuettes for placing on shelves (my PW's drow worship a god of snakes, not spiders)
- semi-transparent holy symbols that can be laid on the floor to appear stained or painted down (for temples)
- headstones with the holy symbol of my PW's goddess of the dead
- a tavern dart/knife/shuriken target that looks like a circle cut from a tree
- fireflies that shine with a bright green light for a moment before "going out" again (because that's what they looked like when I was a kid)
- a "low tech slot machine" with wheels that spin (and stop)...yes, I worked out the (non-existent) inner mechanics in my head before making it
- sewer stuff (floating feces, piles of feces, a floating corpse) because a used sewer shouldn't be clean
More ideas that I haven't seen yet:
- small animal corpses (birds, rats, frogs, fish, etc.) - good for dire omens when a flock of birds has dropped dead in midair
- perfume or cosmetic bottles and jars - something to steal from a merchant or noble house?
- scattered flour - make that kitchen countertop look used, or leave it on the floor
- a saddle - for on the floor or shelf of a stable
- small wooden toys - even D&D kids need something to play with (or leave somewhere)
- hanging plants/herbs - best place to dry them is hanging them from a beam, right?
- mounted antlers - no hunting lodge is complete without them
- tiny glowing runes - for door frames, shelves, altars, big books, or whatever else a wizard wants to mark up
- hanging, gutted corpses - because you don't want your meat to go bad before it's eaten or preserved
- religious props - books, chalices, plates, symbols, knives, incense, scrolls, etc. that are part of ceremonies
- pipes - because Gandalf probably has a couple spares on a shelf somewhere
- boots - clean or muddy, left just outside the door so the house doesn't get dirty
- chandeliers - rich people gotta show off somehow
- beggars sitting on the ground - why waste energy just standing around all the time?
- dice - need something to use for "rolling the bones"