To Paint Foam-iT! Rigid Foam: You can prime and paint the cured surface of rigid foams in the same way that you would cured resin. First prime the casting using 1-2 coats of a high quality auto body primer followed by acrylic enamel paints.
To Paint FlexFoam-iT! Flexible Foam: If you attempt to paint a flexible foam with a standard latex or acrylic paint, the painted surface could crack when the flexible foam part is flexed. You need a paint that will bend and flex with the flexible foam.
Your best option: Maker Pro Paints™ are industrial-grade, professional paints developed for rigorous themed environment applications at amusement parks, zoos, aquariums, etc., where outdoor durability is critical. When mixed with the FLEX Additive, Maker Pro Paints™ will become more elastic and bond to flexible or semi-rigid substrates, including fabrics, semi-rigid urethane resins, flexible urethane foams, urethane rubbers, and latex rubbers.
Other options: UreCoat™ is easily colored with SO-Strong™, UVO™ or Ignite™ colorants to create a permanent paint for coating cured Smooth-On urethane rubbers or flexible foams. In addition, some customers have used our Brush-On 40 urethane rubber thinned with a small amount of mineral spirits as a paint. It is easily color pigmented with SO-Strong color tints. You can also paint the cured surface of flexible foam with fabric paint or flexible acrylic enamel paints. You must make sure the paint adheres to the foam and is flexible after it dries.