In a technique similar to papier-mâché, scraps of linen or papyrus were stuck together with plaster or resin and used to make mummy cases and masks. It could be molded to the shape of the body, forming a type of shell. After the material dried it could be painted or gilded. The shell could be decorated with geometric shapes, deities, and inscriptions. During the Ptolemaic era, the single shell method was altered to include four to six pieces of cartonnage. There would generally be a mask, pectoral, apron, and foot casing. In certain instances there were two additional pieces used to cover the ribcage and stomach.
Reusing papyrus that was considered waste was a common practice during the Ptolemaic period. Many discarded documents from the government and archives were used for this purpose.
The preparation of cartonnage preserved the sections of papyrus; therefore, it is a prominent source of well-preserved manuscript sections. In 1993, the city of Helsinki received fourteen fragments of cartonnages from the Egyptian Museum in Berlin. Conservators were tasked with preserving the cartonnages and publishing all Greek papyrus texts derived from them.