Hollow plastic article

The present invention provides a hollow article for use as a beverage cup 250, or as a container, the hollow article having an annular sidewall 256 and a base wall defining a central hollow cavity, a top rim (208, fig 12) of the sidewall and a bottom end of the sidewall, wherein the annular sidewall comprises a plastics material composed of a sandwich structure 322 of inner 320 and outer 324 skins and an integral expanded cellular foam layer 257 therebetween, wherein at least a portion of the annular sidewall has an inner surface 320 of the sandwich structure inclined at a first acute angle to a longitudinal axis of the hollow article and an opposite outer surface 324 of the sandwich structure inclined at a second acute angle to the longitudinal axis of the hollow article, wherein the second acute angle is greater than the first acute angle. The inner surface may be undulating in a direction extending at least partly around the longitudinal axis of the article. The sidewall may have a thickness at an upper end of the sandwich structure which is greater than a thickness at a lower end of the sandwich structure. A shoulder 321 may define an annular contact ring against which the outer surface 324 of a nested cup may be supported by point contact around the shoulder. The article may also include an annular array of reinforcing areas extending longitudinally along the sidewall, which may include alternating ribs (212, 214, fig 9).