Abstract: Disclosed is a one-piece thermoformed plastic package blank having complementary first and second portions connected by a hinge, with a flange in one plane surrounding the portions and the hinge. The hinge in its central zone is at its maximum height above the flange plane, but is at a lower height in its end zones, tapering off to zero height at its ends, blending into the flange plane. The sidewalls of the hinge are of a negative draft slant undercut in the central zone, but are of a positive draft slant in the end zones of the hinge. To produce the finished package, the blank is die-cut to trim the flange and cut two "V"-shaped notches therein, each notch extending from the flange edge slightly into an end of the hinge, at the point of the "V". The resulting package has smooth hinge end edges and corners, without any sharp protrusions, and it folds properly and easily from open-mode to closed-mode, without application of considerable or excessive force.