Abstract: The invention relates to a method for manufacturing an elastic and flexible fiber with a pre-de-termined non-circular cross-sectional geometry, the method comprising extrusion of an elasto-mer from a nozzle onto a substrate, wherein the pre-determined non-circular cross-sectional geometry of the fiber is determined by the height and velocity of the nozzle relative to the sub-strate. The invention relates to an elastic and flexible fiber produced using the method, wherein the fiber comprises an elongated indentation along a length of the fiber (groove). The invention relates to methods for producing preferably biocompatible microfluidic, electrically conducting or light-guiding fibers using the methods of the invention. The invention further re-lates to elastic and flexible fibers produced by the method.