Abstract: In casting thin metal strip or foil by dynamic casting in which molten metal is teemed from a crucible 13 onto a moving belt or wheel, the invention provides an outlet orifice control assembly arranged to define a slot of controlled width through which the metal flows from the crucible outlet 20. The assembly comprises opposed shut-off plates 28,29 extending between edge strips 26,27, and underlying these are opposed slot plates 32,33 extending between second edge strips 30,31 with opposed support strips 34,35 extending beneath the strips 30,31 and supporting the edges of the slot plates 32,33. The sets of plates are aligned and arranged so that one plate 29 and 33 is movable relative to the other respective plate 28 and 32 between closed and open positions for controlled flow of metal through a sized slot defined between the slot plates 32,33.