Testors is TOO Expensive! I have been experimenting with first painting my Blue-Core FFF planes with MinWax Polycrylic. Then "if you have been careful to cover ALL exposed foam" using any paint you like. So far no issues but still testing. Polycrylic is also good for "glassing" sections of foam planes by bedding a fabric in it. There is a new Krylon H2O Spray Latex but it comes in limited colors and I have yet to find it in a store.