Abstract: Apparatus for forming an end finish on a hollow article having a plastically deformable tubular end portion terminating in an open end of the article. A mold surface surrounds the end portion in juxtaposition with its outer surface, and an expandable tubular membrane is received within the end portion in juxtaposition with the inner surface thereof. The interior of the membrane is sealed from the ambient, elongation of the membrane is restricted, and expansion of the membrane is limited to a lateral zone thereof coextensive with the end portion. The outer surface of the end portion is conformed to the mold surface by subjecting the interior of the membrane to a fluid under pressure to expand the membrane laterally in engagement with the inner surface of the end portion.