A method of making steel comprising: (a) assembling a steelmaking furnace capable of melting and making molten metal for delivery to a first metal delivery system (54, 16, 18) and a second metal delivery system, (b) assembling a thin strip caster capable of continuous casting of steel strip having a thin strip production output, the thin strip caster comprising a pair of casting rolls having a nip therebetween for delivery of thin strip downwardly there from, the first metal delivery system (54, 16, 18) capable of providing molten metal forming a casting pool between the casting rolls above the nip with side dams adjacent the ends of the nip to confine the casting pool, (c) assembling a mold caster capable of continuous casting of steel semi-finished products having a semi-finished production output, the mold caster comprising a casting mold capable of producing one or more strands, the second metal delivery system (54, 58) capable of introducing molten metal into the casting mold, (d) inputting to a computer data on demand for thin strip production output and semi-finished production output, steelmaking furnace availability and capacity for making molten steel, and thin strip caster and mold caster sequence schedules and through-put, capacities and variability, (e) forecasting by processing by computer from the inputted data a production schedule for the steelmaking furnace, a sequence schedule for the thin strip caster, and a sequence schedule for the mold caster as a function of molten metal availability for casting in the strip caster and mold caster, the thin strip caster and mold caster sequence schedules and through-put, and the demand for thin strip production output and semi-finished production output, and (f) directing production of the molten metal from the steelmaking furnace alternatively to the first delivery system (54, 16, 18) of the thin strip caster and to the second delivery system (54, 58) of the mold caster responsive to said forecasting. (a) assembling a steelmaking furnace capable of melting and making molten metal for delivery to a first metal delivery system (54, 16, 18) and a second metal delivery system, (b) assembling a thin strip caster capable of continuous casting of steel strip having a thin strip production output, the thin strip caster comprising a pair of casting rolls having a nip therebetween for delivery of thin strip downwardly there from, the first metal delivery system (54, 16, 18) capable of providing molten metal forming a casting pool between the casting rolls above the nip with side dams adjacent the ends of the nip to confine the casting pool, (c) assembling a mold caster capable of continuous casting of steel semi-finished products having a semi-finished production output, the mold caster comprising a casting mold capable of producing one or more strands, the second metal delivery system (54, 58) capable of introducing molten metal into the casting mold, (d) inputting to a computer data on demand for thin strip production output and semi-finished production output, steelmaking furnace availability and capacity for making molten steel, and thin strip caster and mold caster sequence schedules and through-put, capacities and variability, (e) forecasting by processing by computer from the inputted data a production schedule for the steelmaking furnace, a sequence schedule for the thin strip caster, and a sequence schedule for the mold caster as a function of molten metal availability for casting in the strip caster and mold caster, the thin strip caster and mold caster sequence schedules and through-put, and the demand for thin strip production output and semi-finished production output, and (f) directing production of the molten metal from the steelmaking furnace alternatively to the first delivery system (54, 16, 18) of the thin strip caster and to the second delivery system (54, 58) of the mold caster responsive to said forecasting.