Despite the section name, what belongs here is stainless steel mixing balls between 2 and 4 mm rather than hollow micro balloons. They do one job well: dropped into a bottle of paint, wash or liquid pigment, they roll through the settled material as you shake it and break up the compacted pigment at the bottom that shaking alone never reaches. A bottle agitated badly gives you medium with hardly any colour in it.
Two or three balls per bottle is enough; too many simply take up volume. Stainless steel will not rust in a water-based medium, so they can be left in permanently, and the rattle is a useful reminder that a bottle has actually been shaken. They are worth adding to anything that settles hard — bottles from model paints and especially heavily loaded pigment suspensions. The rest of this branch, from putties to holders, is listed under sculpting tools and materials.
