Abstract: A procedure and device are provided by means of which a coextruded sheet including an intermediate layer with multiple longitudinal strips of various colours that are perfectly delimited between each other without the colours in every two adjacent strips becoming mixed, the sheet being formed by simultaneously extruding the three layers forming it, employing a plurality of extrusion material conducts in one single extrusion head provided with adjustable passage capability, a conduct for each upper and lower layer and one for each colored strip in the intermediate layer, so that by controlling parameters such as pressure, speed and flow volume, strip uniformity is achieved in regard to both thickness and width.