Shaking Your Paint Bottles
I found a great tip online for mixing your paint bottles. Go to the bead store and buy a strand of 8mm lava beads (although other glass beads would probably work also). They don’t affect your paint and are heavy enough to mix the paint.
www.dakkadakka.com/wiki/en/Paint_Agitators
I’m going to add a second tip to that… maybe you could put 2-3 beads on a piece of nylon filament, tie the end and leave it long enough to drop the beads in your bottle of paint and the filament hanging over the edge of the bottle. Put the lid back on and shake, then you can lift the beads back out and wash them to use again. Of course, you will waste a little paint that coats the beads, but I’m thinking plastic bb’s or any other beads may stop up the hole in the lid when you try to squeeze out your paint.