Discussion of rectangular pottery containers (‘bricks’) with a recessed image of Osiris, together with a catalogue of extant examples. These are related to the Festival of Khoiak, when images of Osiris were made of soil and grain. The containers are defined as matrices for the creation of such Osiris figures. Their date and a western Theban provenance are suggested through discussion of Osirian cult activity, particularly at Medinet Habu, during the Third Intermediate and Late Periods.