A method of forming a vacuum insulated refrigerator cabinet, the method comprising: providing first and second sheets of material (20, 22) comprising at least a first layer of thermoplastic material, and a second layer of material that is substantially impermeable to oxygen, nitrogen and water vapor; heating at least a portion of the first sheet of material to a temperature at which the first sheet of material can be plastically deformed; utilizing a first forming tool to deform the first sheet of material and form a first intermediate structure having a base sidewall and a plurality of first sidewalls extending transversely from the base sidewall to define a cavity having an opening and defines a peripheral edge extending around the opening; providing a second forming tool having sidewall portions defining a plurality of outwardly facing surfaces and a plurality of inwardly facing surfaces, and at least one end surface extending transversely between the inwardly and outwardly facing surfaces; disengaging the first intermediate structure from the first forming tool, followed by positioning the second forming tool in the cavity of the first intermediate structure; plastically deforming the base sidewall to form a second intermediate structure having a base sidewall and a plurality of inner sidewalls extending transversely from the base sidewall, wherein the plurality of inner sidewalls are spaced apart inwardly from the first sidewalls to define an annular space; sealingly connecting the second sheet of material to the second intermediate structure around the peripheral edge to substantially close off the opening; filling the annular space with a highly porous insulating material; and forming a vacuum in the annular space. providing first and second sheets of material (20, 22) comprising at least a first layer of thermoplastic material, and a second layer of material that is substantially impermeable to oxygen, nitrogen and water vapor; heating at least a portion of the first sheet of material to a temperature at which the first sheet of material can be plastically deformed; utilizing a first forming tool to deform the first sheet of material and form a first intermediate structure having a base sidewall and a plurality of first sidewalls extending transversely from the base sidewall to define a cavity having an opening and defines a peripheral edge extending around the opening; providing a second forming tool having sidewall portions defining a plurality of outwardly facing surfaces and a plurality of inwardly facing surfaces, and at least one end surface extending transversely between the inwardly and outwardly facing surfaces; disengaging the first intermediate structure from the first forming tool, followed by positioning the second forming tool in the cavity of the first intermediate structure; plastically deforming the base sidewall to form a second intermediate structure having a base sidewall and a plurality of inner sidewalls extending transversely from the base sidewall, wherein the plurality of inner sidewalls are spaced apart inwardly from the first sidewalls to define an annular space; sealingly connecting the second sheet of material to the second intermediate structure around the peripheral edge to substantially close off the opening; filling the annular space with a highly porous insulating material; and forming a vacuum in the annular space.