The invention relates in summary to a method and a device for applying at least one material (3, 5) to a substrate or a workpiece (WS), an extruder, a 3D print head, a 3D printer and a machine tool. The invention also relates to a control device. The device has a main body (1) with an outlet (7) for the materials (3, 5). The materials (3, 5) are fed through at least two access channels (2A, 2B) tothe outlet (7) and mixed and/or blended there. A rotational movement of the main body (1) with respect to the substrate or the workpiece (WS) has the effect that the materials (5, 6) are blended in away analogous to a double helix or a plait. Mixing/blending of the materials is advantageously improved by the invention. If applied to a 3D printing process, either the workpiece (WS) rotates aboutan axis of rotation (d), which extends through the outlet (7) of the main body (1), or the main body (1) and consequently the outlet (7) itself rotates.