the daughter of of William Harbutt's (inventor of plasticine) was an inspirational plasticine painter. Her paintings would have made great plasticine paint by numbers kits. http://www.instructables.com/id/How-to-make-your-own-Van-Gogh-paint-by-numbers-Pai/
One of my favourite book illustrators Barbara Reid
also inspired this Playdough Painting class for children. Why not play dough I thought. Here's the result of a short session with mushy playdough. Even the mum's and dad's had a go. I kept the playdough in an uneven marbly state which added a rather nice subtle effect to the paintings.