Tissue paper, £1 from the £1 shop, I know, I don't like buying materials, but I don't have any lying around, and I can afford £1. There is tons of it, lots of different colours, plenty for other projects.
Cut some into small shapes, squares, circles, triangles, hexagons, whatever. I tried it first on a small board, I have some board, got it at the Scrapstore. If you are going to do this you could use thick paper. Lay the pieces out to whatever design you like, then wet a brush (tap water) and stick the shapes to the board.
Now where was I. Ooops, Garcia has decided that he would like to lie on it, oh well, I'll get on with my other projects then. He is not my cat, he lives two doors up the road, but he visits daily, he sleeps in his own house at night. After nearly ten years of commuting I haven't the heart to throw him out, he is an old boy. His owners know where he is.