Snake,
If I may, let me clarify what you are referring to, just to save someone from having to trash some plastic or from serious injury. Artist paint tubes will work fine because they are mostly powder pigments. The oil based paint that comes in gallons that you might paint a door with WILL NOT work in plasticols. Being a commercial/industrial paint contractor I stopped in at sherwin williams with the MSDS sheet looking for a more economical tint for the plastic. My thinking was, if their tint will work all I have to do is supply the heat stabilizer and let them shoot the tint for all of the colors that I was wanting, why not they have the color matching computer, got it made. Well talking with the chemist on the 800 number I found out they use a different kind of tint and even there epoxy tints would not work. Thought it would be too easy.
Artist tubes will work in a pinch, however it is more costly in the long run using this instead of the liquid or powder tints made for it.