EPSILON™ Series, EPS Foam Coating Epoxy | Smooth-On, Inc.
Gel Coat FRP Smooth Finish - China FRP Smooth Finish, Smooth FRP Finish | Made-in-China.com
UreCoat™ - The Compleat Sculptor
How to Coat Styrofoam | ehow
What can I use to coat this styrofoam so I can paint it? : r/TerrainBuilding
Terrain idea: Tried to smooth styrofoam, turns out enamel spray and acrylic clear coat have some interesting cratering effects instead. Could be useful. That said, like any spray painting, do it outside.