A portable concrete molding machine can extrude concrete moldings of a range of widths by the provision of one or more tunnel plates within the mold, the machine being provided with respective pusher plates that have pusher faces of widths complementary to the effective widths of the mold. A pair of links connect a gearbox to the pendulum arms of the pusher means to ensure even driving force applied to the pusher plates as they undergo reciprocating movement to allow concrete to flow from a hopper through a mouth of the mold and to extrude the concrete from the mold, the machine being advanced in an extrusion direction by the extrusion of the concrete from the mold.