A method and apparatus for manufacturing an otoplastic. An otoplastic is manufactured directly in the ear of a hearing-impaired person in that a deformable envelope is pulled over a die or over a shell or over an overlayed over-shell. This apparatus is then supplied with flowing otoplastic material between the die and the envelope, being supplied therewith in the ear. The envelope expands and assumes the shape of the auditory canal. After hardening or curing of the otoplastic material in the ear of the hearing-impaired person, the envelope and the die are removed and a module of either an in-the-ear or of a behind-the-ear hearing aid is integrated therewith.