Abstract: A molding apparatus for molding in place walls of a structure on a poured concrete floor or other base is provided with a central support member to which are movably attached four flat wall molds and four corner molds which cooperate with adjacent like apparatus and also with conventional exterior molds in forming a cast structure; the apparatus has actuating members for effecting retraction firstly of the flat wall molds and then of the corner molds toward the central support member upon completion of a casting operation and after hardening of the cast materials; the flat wall and corner molds are connected to the central support member by means of a plurality of lost motion connectors in such a manner that the aforementioned retraction is accomplished, after disengagement of locking devices, first by the flat wall molds and then, after a selected delay, by the corner molds; then, while in this position, the apparatus is removed and transported to another location where it will be set in its place in an expa