Abstract: A method of forming cast concrete modules made of a floor, two spaced apart upstanding walls, and a roof extending between the walls. The method uses casting beds in groups of four and one set of forms, two interior and two exterior forms, which are movable from bed to bed. By performing different steps of the method on different casting beds on different days, separate modules can be erected progressively on separate beds in a group of four, so that with one set of forms and one group of beds, three modules can be produced every eight consecutive days.