Methods and systems for integrating multiple portions of a container are provided. The method and system are specifically designed for integrating multiple shell portions with ear lobe-shaped tabs. The method comprises: providing a first set of retention structures to be associated with a plurality of inter-connecting features formed on an edge of a first shell part, wherein the first set of retention structures comprise at least a lead-in feature and a retention feature; providing a second set of retention structures to be associated with a plurality of inter-connecting features formed on an edge of a second shell part, wherein the second set of retention structures comprise at least a deflection feature and a retention feature; and engaging the two shell parts with aid of the retention structures.