Twin roll caster for casting metal strip comprises pair of parallel casting rolls forming nip to receive molten metal from elongate metal delivery nozzle formed in two pieces supported in end to end relationship with a gap between them. A pair of casting pool confinement plates are thrust against the ends of rolls by thrusters mounted with the side plastes on carriages forming part of moveable structures which are connected to the outer rends of nozzle pieces by pins and which can be moved by operation of screw jacks. The outer ends of nozzle segments can be accurately set in position relative to side plates prior to a casting and during a casting operation screw jacks can be operated so as to move the nozzle segments inwardly to match inward advance of the side plates as they wear.