10 ethylene vinyl acetate 88 iron powder filler with the balance of the composition consisting of stabilizers and processing aids and is manufactured by cast extrusion one such suitable material is manufactured by the dupont company and is described in their published canadian patent application no 2 003 879 of nov 24 1989 other suitable binder materials for the substrate comprise low modulus ethylene copolymers selected from the group consisting of ethylene methyl acrylate ethylene ethyl acrylate ethylenemethacrylic acid and ethylene butyl acrylate and maleic anhydride grafts thereof also suitable are polyvinylchloride ethylene propylene synthetic rubbers and ethylene propylene elastomer with a reactive monomer graft as well as a group consisting of a copolymer of ethylene and methacrylic acid and a copolymer of ethylene and ethylene acrylic acid a further suitable group will be a variety of thermoplastics including specifically polypropylene polyethylene polycarbonate polystyrene acrylonitrile butadiene styrene terpolymer polyphenyleneoxidepolystyrene blends acrylic polymer polyurethane and polyamides the display surface is composed of an extrusion laminate of semi rigid plastics such as polyvinylchloride and the sheet is preferably 0 175 to 0 750 mm in thickness the display surface may be plain white and as such can receive wet or dry markers can be provided with an overlaid graphed or charted surface for example by silk screening to facilitate the presentation of information with the application of magnetic symbols and information or indeed could have a printed chalk compatible surface for use with chalk other uses include a matt surface applied over the polyvinylchloride to produce a flexible portable projection screen as seen in fig2 the display surface is attached over the substrate as an overlay and secured thereon by adhesive one method of adhering the display surface on to the substrate is to mechanically.