disclosed are a top shell or bottom shell made from a deep - drawn molded plastic part as well as a receptacle which is composed of the two joined shells . the invention further relates to a method and a device for producing a top shell or a bottom shell . the aim of the invention is to create a first and second shell which can be produced inexpensively as a disposable item while allowing the same to be locked together in a fixed but easily removable manner by joining the two shells together so as to create a largely tight receptacle . said aim is achieved , among other things , by embodying a reducing collar between the holding edge and the pot - type central part on the top shell while disposing at least two identically pitched threads on the inner face of the holding edge . the reducing collar delimits the at least two threads on one side while said at least two threads are provided with an open thread inlet .