Smooth Foam Bells Available in 4 Sizes Hollow Core EPS - Etsy
Foam Coat
Bulk All Purpose Foam Coat...
Smooth-on Urecoat Flexible Coating - Stage and Screen FX
A one-step method to coat polystyrene particles with an organo-silica shell and their functionalization - ScienceDirect
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.
UreCoat™ Product Information | Smooth-On, Inc.
EPSILON™ Series, EPS Foam Coating Epoxy | Smooth-On, Inc.
UreCoat™ - The Compleat Sculptor
How To Coat Carved EPS Foam Using Habitat Cast N Coat™ Epoxy - YouTube
Create Coat Foam Coating - 3lbs #027 | eBay
Create Coat Foam Coating - 3lbs #027 | eBay
White Styrofoam/polystyrene/eps Foam Block 12 X - Etsy