Abstract: A method of making a hinge joining two rigid pieces each with top and bottom surfaces, comprising the steps of thermoforming a first piece of rigid plastic material having a first hinge joint; machining a hole with a tubular shape through each of two external surfaces of the first hinge joint; thermoforming a second piece of rigid plastic material having a second hinge joint; machining two keyhole-shaped passage perpendicular to the length of the surface and across the width of the near-end external surfaces of the first protrusion and of the second protrusion of the second piece; inserting a hinge pin through each hole with a tubular shape; and assembling the two pieces with the first hinge joint fitting into the gap of the second hinge.

Abstract: A hinge joining two rigid pieces. A first hinge joint protrudes from a first piece of rigid-plastic material, and has two surfaces. Each of the two surfaces of the first hinge joint has a hinge hole with a tubular shape. A second hinge joint protrudes from a second piece of rigid plastic material. The second hinge joint has a first hollow and a second hollow. The space between the first hollow and the second hollow define a gap length which approximately is equal to the hinge-joint length such that the first hinge joint fits between the near-end surfaces of the first hollow and the second hollow. Each of the near-end surfaces of the first hollow and the second hollow has a keyhole-shaped passage. The hinge pin passes, aligned, through the hinge hole of the first hinge joint, and the tubular central portion of each of the keyhole passages. The hinge pin hinges together the first piece and the second piece.

Abstract: A hinge joining two rigid pieces. A first hinge joint protrudes from a first piece of rigid-plastic material, and has two surfaces. Each of the two surfaces of the first hinge joint has a hinge hole with a tubular shape. A second hinge joint protrudes from a second piece of rigid plastic material. The second hinge joint has a first hollow and a second hollow. The space between the first hollow and the second hollow define a gap length which approximately is equal to the hinge-joint length such that the first hinge joint fits between the near-end surfaces of the first hollow and the second hollow. Each of the near-end surfaces of the first hollow and the second hollow has a keyhole-shaped passage. The hinge pin passes, aligned, through the hinge hole of the first hinge joint, and the tubular central portion of each of the keyhole passages. The hinge pin hinges together the first piece and the second piece.