A method for producing a multi-layer, microcapillary film, comprising: passing a thermoplastic material into an extruder; characterized in that the method further comprises: passing the thermoplastic material through a die assembly operatively connectable to an outlet of the extruder, the die assembly comprising: a pair of die plates (356a,b); a manifold positionable between the pair of die plates and defining a plurality of film channels (470a,b) therebetween, the manifold comprising an intake and an outtake, the outtake having a tapered outer surface extending to an elongate nose, the plurality of film channels converging into an elongate outlet; and a plurality of nozzles positionable between the plurality of film channels and in a linear configuration along the elongate nose and adjacent the said elongate outlet, the plurality of nozzles operatively connectable to a source of channel fluid; selectively adjusting a profile of the multilayer film by manipulating one of temperature, flow rate, pressure, material properties and combinations thereof of the thermoplastic material; forming the multi-layer film by extruding the thermoplastic material through the plurality of film channels and the elongate outlet; and forming microcapillaries in the multi-layer film by emitting the channel fluid between layers of the multi-layer film with the plurality of nozzles. passing a thermoplastic material into an extruder; characterized in that the method further comprises: passing the thermoplastic material through a die assembly operatively connectable to an outlet of the extruder, the die assembly comprising: a pair of die plates (356a,b); a manifold positionable between the pair of die plates and defining a plurality of film channels (470a,b) therebetween, the manifold comprising an intake and an outtake, the outtake having a tapered outer surface extending to an elongate nose, the plurality of film channels converging into an elongate outlet; and a plurality of nozzles positionable between the plurality of film channels and in a linear configuration along the elongate nose and adjacent the said elongate outlet, the plurality of nozzles operatively connectable to a source of channel fluid; selectively adjusting a profile of the multilayer film by manipulating one of temperature, flow rate, pressure, material properties and combinations thereof of the thermoplastic material; forming the multi-layer film by extruding the thermoplastic material through the plurality of film channels and the elongate outlet; and forming microcapillaries in the multi-layer film by emitting the channel fluid between layers of the multi-layer film with the plurality of nozzles. passing the thermoplastic material through a die assembly operatively connectable to an outlet of the extruder, the die assembly comprising: a pair of die plates (356a,b); a manifold positionable between the pair of die plates and defining a plurality of film channels (470a,b) therebetween, the manifold comprising an intake and an outtake, the outtake having a tapered outer surface extending to an elongate nose, the plurality of film channels converging into an elongate outlet; and a plurality of nozzles positionable between the plurality of film channels and in a linear configuration along the elongate nose and adjacent the said elongate outlet, the plurality of nozzles operatively connectable to a source of channel fluid; a pair of die plates (356a,b); a manifold positionable between the pair of die plates and defining a plurality of film channels (470a,b) therebetween, the manifold comprising an intake and an outtake, the outtake having a tapered outer surface extending to an elongate nose, the plurality of film channels converging into an elongate outlet; and a plurality of nozzles positionable between the plurality of film channels and in a linear configuration along the elongate nose and adjacent the said elongate outlet, the plurality of nozzles operatively connectable to a source of channel fluid; selectively adjusting a profile of the multilayer film by manipulating one of temperature, flow rate, pressure, material properties and combinations thereof of the thermoplastic material; forming the multi-layer film by extruding the thermoplastic material through the plurality of film channels and the elongate outlet; and forming microcapillaries in the multi-layer film by emitting the channel fluid between layers of the multi-layer film with the plurality of nozzles.