molded condition a median 530 longitudinal and transverse of the hinge is generally upwardly convex along the central portion the relative convexities and concavities are such that the central portion 96 is centrally relatively thick and thins away from a location 98 fig5 proximate the hinge center in both directions lateral and proximal distal curvature changes along the length of the hinge so that the exemplary face 88 is lengthwise concave and 90 lengthwise convex in a proximal region of the hinge and along a distal region their respective convexity and concavity decreases relative to the central portion fig7 shows a central thickness t 1 and a thickness t 2 at or near the hinge edges an exemplary thickness decrease from center to edge is of at least 30 fig7 shows a hinge width w 1 exemplary w 1 is one inch 2 5 cm largely depending on container lid size weight etc but likely typically 0 5 1 5 inch 1 3 3 8 cm or 0 75 1 25 inch 1 9 3 2 cm in the as molded condition the first end 80 and second end 82 are generally horizontal with the second end spaced upward from the first end an exemplary vertical offset h 1 is at least 50 of a horizontal separation s 1 more narrowly close to 100 e g about 80 120 in an exemplary implementation t 1 is 0 057 inch and t 2 is 0 023 inch fig3 a similarly shows thicknesses t 3 and t 4 respectively near the ends 80 and 82 in the exemplary embodiment t 3 is 0 05 inches 1 3 mm from edge to edge and t 4 varies from a low value 0 021 inch 0 53 mm at the edges to a relatively.