Sorry for taking about a billion years to respond, the group doesn't see much activity anymore and I forget to check it! Generally acrylic paints are recommended, but you can use any water-based paint on them; you can test your paint out on an inexpensive "must" PYO if you aren't sure if it will react well. Oil and enamel based paints are not recommended as the gypsum likes to be able to "breathe" and oil/enamel type paints might crack over time.
