this is mouldy as fuck

My bet (or hope) is that items stack with each-other still, even if they're of differing quality. Maybe when you hover over a stack of items in a slot, it'll show how many of each quality you have, and you can select/split specifically?
Though, inventory size is supposed to be further increased by higher-quality modular armours, which may also help...

Talking about a Main Bus, which (IIRC) is a large road of belts to hold every common/general material en masse