Hey guys I will be attempting my first go at this once iv got enough polystyrene together was just wondering if this is the right stuff to cover it in? An is there anything else I would have to do to once I have done about 5 coats of it http/www.diy.com/nav/decor/decorating-supplies/fillers-putty/fillers/-specificproducttype-interior_fillers/Polycell-Quick-Set-Cement-Polyfilla-PC3650017-Grey-9254184?noCookies=false thanks in advance