Although I get a lot of flyers in the mail normally, I am getting a lot more now. People sending advertising through the mail now are using business sized or even larger stiff cardboard flyers, that are plasticized on both sides. I am finding a variety of uses for these things, and are happy to get them even if I don't pay any attention to real them.
I have long used them as pallets, for CA glue, and for daubs of paint when drybrushing. They are great pallets because they do not absorb thin CA or thinned paint.
I have found they are great for scribing lines. I put a piece of double sided tape near one edge and can follow along that edge with my scalpel. I have even used them as armored shields to replace the kit parts that are too thick. Because of that plastic coating on both sides, they can be primed and painted just like plastic.