paint for foam

Anything water base will work, including latex if you want to go cheap. In the quantity you will need it in, however, I use water based acrylics available at craft stores. A buck or 2 for a bottle. It's best if you thin it out with water and spray it on with an airbrush if you are going to paint the entire plane. It will build up less weight that way. Of course, you can thin it out to paint it with a brush, too. If you are trying to paint a light color over dark, you will need to use it uncut, or use a lot of coats. Buttercream is my favorite color for a nice antique (yellowed) white.

I use Walmart Craft paint. No weight buildup, Cheap, lots of colors, and gloss and flats for camos.