Bistable hinge with reduced stress regions

A hinge structure for a closure for a container opening wherein said closure includes (1) a base for mounting to said container over said opening and defining a discharge aperture communicating with said opening, and (2) a lid movable between a closed position occluding said aperture and an open position spaced from said aperture, said hinge structure comprising:

• a bistable, snap-action hinge structure molded as a continuous structure unitary with the base and lid to include (a) a web having a central, narrow portion between two wider ends which each defines a lateral edge, (b) an arcuate hinge that connects said base to said web along one side of said web between said lateral edges, and (c) an arcuate hinge that connects said lid to said web along another side of said web between said lateral edges, each said hinge bending to permit said web to move through a range of orientations relative to said base and lid, said web having two spaced-apart reduced thickness regions, each said reduced thickness region extending to one of said lateral edges and having a reduced thickness at said lateral edge relative to the thickness of adjacent portions of said web at said lateral edges.