The present invention relates to a multistage process for producing hollow plastic articles, encompassing the following steps: a) producing a tubular plastic parison by means of extrusion or coextrusion; b) cutting open the plastic parison to produce two planar-surface parts; c) molding the planar-surface parts in two mold halves to give half shells, where a removable intermediate frame separates the mold halves from one another at least along the peripheral edges, so that the semifinished products/half shells are not in contact with one another; d) opening the mold halves and removing the intermediate frame; e) closing the mold halves, with the result that the half shells come into contact with one another along a peripheral rim; and f) bonding the half shells to give a hollow article.