NOVELTY - A coextrusion ink set comprises a first ink lacking a yield stress and a high viscosity; one of a second ink or a sacrificial material lacking a yield stress and a high viscosity; and a material having a finite yield stress or a high viscosity is formed at an interface of the first ink and the one of the second ink or sacrificial material as a result of localized mixing of the first ink and the one of the second ink or sacrificial material.    USE - As coextrusion ink set useful in coextruded print system (claimed); for making fine conductive or ceramic lines or structures; for forming conductive lines for solar cell fabrication, for forming barrier ribs (pixel separators) in plasma display panels, forming components of thick film heaters and for forming components in fuel cell applications; for solar cell production.    ADVANTAGE - The material having a finite yield stress or high viscosity prevents mixing of the first ink and the one of the second ink or sacrificial material beyond the localized mixing which formed the material having a finite yield stress or high viscosity. Such higher aspect ratios are achievable as a result of the presence of the material having a finite yield stress or high viscosity. The material having a finite yield stress or high viscosity maintains the mechanical dimensions of the ink structure, as it was coextruded, against a variety of forces that would otherwise cause the structure to deform before its shape can be set by drying and/or firing. The material having a finite yield stress or a high viscosity has a yield stress greater than 1000 Pa, and a thickness of greater than 1 mu m. The material having a finite yield stress or a high viscosity maintains mechanical dimensions of a structure deposited on a substrate. The structure obtained by using the coextrusion ink set has high aspect ratios i.e. an aspect ratio of greater than 0.3, and/or the structure has a height of 10-250 mu m. The ink has a composition such that it lacks a yield stress and a high viscosity, i.e. has a yield stress of less than 100 Pa and a zero-shear viscosity of less than 50 Pas. As a result of substantially lacking a yield stress and a high viscosity, the ink composition can easily be passed through the extruder printhead, without the need for large amounts positive or negative pressure.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a coextruded print system comprising a substrate; and a bead located on the substrate, where the bead comprises a first ink lacking a yield stress and a high viscosity, and one of a second ink or a sacrificial material, lacking a yield stress and a high viscosity, where the first ink is situated in a first region of the bead, and the one of the second ink or sacrificial material is situated in an adjacent second region of the bead; and the bead further comprises a material having a finite yield stress or a high viscosity between the first ink and the one of the second ink or sacrificial material.