The present invention provides multilayer sheet structures especially suited for thermoforming applications such as refrigerator cabinet and door liners comprising a surface non-foamed layer A and a surface foamed layer B having a total sheet thickness of from about 0.5 to about 20 millimeters (“mm”). Improvements in thermoformability, including cycle time reduction and polymer and energy savings, are provided. Preferably the non-foamed thermoplastic polymer surface layer (A) has a thickness of from about 0.25 to about 6 millimeters and the foamed thermoplastic polymer surface layer (B) together with any other foamed polymer layers have a total density reduction of at least about five (5) weight percent and have a total thickness greater than the total thickness of the non-foamed layer A together with any other non-foamed layers. Also provided are improvements in the thermoforming process, thermoformed articles, processes for providing thermally insulating articles and thermally insulating articles.