Here is a electric foam model purchased from Rapid RC Models (rapidrcmodels.com). This model FLYCAT has been completely covered with 25g Ultra lightweight glass fibre woven cloth and 'wetted' with Bucks Single-Part coating system. Please see the 'How To Do' for more information. This system doesn't add much weight to the model. This system makes a good base layer with glass fibre woven cloth for painting foam models and can be easier cleaned.
When covering a foam surface, sand the foam smooth then cut the glass fibre woven cloth to size and lay on the foam surface. Now wet out the cloth with the Bucks Single-Part coating system with a coating brush or a roller then leave for 2 hours to dry before applying another coat. Repeat the process until the required finish is achieved.