Treehugger
I think having mixed paint in separate bottles is a good idea, if you need to spray a lot of paint. Otherwise I think a 10ml glass jar is ok. After mixing my paint in my 10ml jar and pouring the contents into my airbrush, I quickly clean the jar and wipe it dry. I also like filling the jater with water to dry remove any fibers that maybe came from the tissue paper I used to wipe the mixing jar dry. Then I place the mixing jar, upside down on the table.

I use a tea sift, to try catch flakes of paint off Vallejo primer and paint bottles, there clearly are flakes coming off the primer bottles. I then quickly try clean the most of the paint in the sift with semi-lint free tissue paper (but has loose fibers), and then I place the sift into a container of water, so I don't have to pause my work to fully clean the sift, I can do that later.

Once you notice that your regular loose Vallejo paint bottle aren't flowing when you press the bottle holding it downwards, be careful and avoid pressing too hard, ELSE, you risk the loose top nozzle popping out and paint pouring out. 😄

I have both stainless steel balls, and glass spheres. I initially bought a big bag of glass spheres, and I am very happy with that. I only boght the metal ones later on to try them out. 🙂

Wim van der Luijt
@Valters Orlovskis: Not all stainless is magnetic 😄 so your mileage may vary