Mike, you are right... whoever made the clam shell container for SEARS must be very experienced in making a one part mold with two hinges. We are now looking into using a sheetmetal part with 6 individual segments with each end formed (like a door hinge) with pins connecting same. Cost would be...
Our need is for a strip (2"x1/8" cross section) of suitable hinge type plastic where there are a total of six hinge notches across the width of the strip. A web search with Google (Plastic Hinges) shows two suppliers at the top of the search results. They offer short hinges and piano type hinges...
