For the last couple of years my junk mail has included these large cardboard postcard-like flyers, anywere from about 4 x 6 to about 5 x10, that are plastic coated. I save these as modeling supply. I cut them up and use them for pallets for CA glue and for paint for drybrushing. Left intact, they can be used for practice painting. The plastic coating is thick enough that the cards paint just like styrene.