Wife works at a compound pharmacy... She's brought home several different kinds of containers. I will say that some of my favorite for doing small test mixes are little bitty ones with snap lids. Think they may be for contacts or something.
Only thing about the really small container is, for me, I tend to dip kinda aggressively and I have once or twice touched the bottom of the cup with the jighead and touching that plastic with a hot jighead made a "blemish" in the finished paint. Maybe I need to practice a lighter touch when dipping.