Tray and manufacture thereof

A tray comprising:

• an annular sidewall having upper and lower annular peripheral edges, an upper annular peripheral rim which is integral with the upper annular peripheral edge, and a base which comprises an annular peripheral edge which is integral with the lower annular peripheral edge of the sidewall, wherein the rim, the sidewall and the base are composed of a thermoplastic polymer and the sidewall and the base define a central concavity for packaging a product, wherein the base comprises a lattice structure of elongate foam ribs interconnected by foam junctions, wherein each foam rib has opposite ends, and each end is integrally connected to either the annular peripheral edge of the base or one of the foam junctions, wherein each foam rib and each foam junction comprise opposed upper and lower unfoamed solid skins of the thermoplastic polymer on opposite sides of a central cellular foam core of the thermoplastic polymer, wherein the lattice structure is an open framework with a plurality of openings, each opening being surrounded by a plurality of the elongate foam ribs, or by at least one of the elongate foam ribs and a portion of the lower annular peripheral edge, and wherein the base further comprises a flexible sheet which is bonded to the lattice structure and to the annular peripheral edge of the base to cover the openings and form a sealed base surface of the tray.