All of the artist OIL paints that I have tried work well with the plastisol. They are pigments so don't bleed. One of the problems
is measuring volume from a OIL paint tube to replicate a new batch of plastic. The paints are well concentrated and the volumes
can be quite small. I made a tool from 1/2 x1/8 aluminum stock with a series of holes drilled. You squeeze a hole full-
wipe it flush and stir it into the plastisol. Heating the plastisol too just below the jell state helps to clear the hole.