Container having interlocking base and closure

A container having a base and interlocking closure therefor, said container base comprising a bottom wall, a peripheral hollow side wall extending therefrom, said side wall having an inner peripheral wall portion and an outer peripheral wall portion joined by a flat outer face, said outer wall portion being stepped along a line spaced from said outer face forming an inwardly extending shoulder, said flat outer face and adjoining corners being of relatively heavy thickness with the wall of the stepped portion adjoining said shoulder being thinner than said outer face and said adjoining corners, said closure comprising a top wall and a peripheral hollow side wall extending therefrom, the last said side wall having an inner wall portion and an outer wall portion joined by a flat outer face, said inner wall portion being stepped near the edge thereof forming an inwardly extending shoulder, the last said flat outer face and adjoining corners being of relatively heavy thickness with the wall of the stepped portion adjoining the last said shoulder being thinner than the last said flat outer face and adjoining corners, the outer periphery of the first said flat outer face of said container base being substantially the same in size and configuration as the inner periphery of the flat outer face of said closure whereby said container base and closure will firmly interlock upon being pressed into engagement.