Immature stages of many species of chrysomelid leaf beetle recycle their feces into body coats, portable cases and mobile shields. The architecture, functions, associated morphology and phylogenetic origins of these structures have not been well-studied. This paper presents the first extensive study of case architecture in the cryptocephaline tribe Chlamisini. A terminology and model for describing cases is developed using ten chlamisine taxa. Within a single life history the maternally-initiated egg case is extended and widened through each of four larval instars and eventually sealed to provide a pupation chamber. Intra- and interspecific variation involve changes in shape, dimensions, fecal texture, and incorporation and density of plant trichomes. Deviations of the chlamisine case from a simple geometrical gnomon are explained by the changing body size of the animal, weight of the case, and shifts in the orientation of carriage of the case. Potential phylogenetic characters from case architecture are proposed.