I use coffee cans.
I wash them out with dish soap for the obvious reasons and bring them to work and put a piece of tape on the lid with either SG for semi-gloss , C for ceiling paint, or W for the Wall paint.
The plastic lid keeps crap out and the freshness in.
Also, when not in use even for a few minutes, a put the lid on and I don't have to worry about the dip****s I work with knocking it over and spilling paint all over the place.
They use empty,(we usually don't have running water)dirty old Dunkin Donuts coffee cups.
Not only is it lousy coffee, but these clowns are always knocking them over and running to me to borrow my rags to clean up the mess.
Slows us down and wastes time.