We have a wide range of polystyrene balls/ spheres from 20mm diameter, all the way up to 400 mm diameter. The larger balls are supplied in hollow halves witch fit together, with the smaller polystyrene balls being solid. Unlike most of the polystyrene (some times referred to as Styrofoam) balls available in the UK, ours contain a flame retarding additive, which make them suitable for commercial window display use, as well as craft use for decorations etc. The polystyrene balls make great Craft and modelling materials, and can be paintd with water or acrylic based paints. You should not paint the polystyrene balls with spirit based painte, or most spray paints, as these will dissolve the polystyrene.
We have large UK stocks of the polystyrene balls are are able to meet large orders quickly.