if we're talking about the same thing-
I use a rectangular tub -w- a lid that pesto came in.
- put a not sopping wet folded paper towel in the bottom.
- cut a slightly larger than the bottom of the container piece of parchment paper in the bottom.
- add paint and then ~paint the minis
The main benefit is that the paint remains viable for a long time, a few weeks. This is especially good if you are mixing up a custom color and are painting a unit as I usually am. Or when painting up a unit and you need to go touch up something you don't need to blob out more paint.
Of course I paint strictly to get figures on the table and not for any showcase or award so I'm sure that any subtleties of the technique are lost on me.