A method of making an optical fiber with multiple openings comprising the steps of fabricating an extrusion die using additive manufacturing such that the extrusion die has a plurality of channels that combine inside the die into another set of channels, extruding a glass, forming a fiber optic preform having a plurality of longitudinal openings that run the entire length, attaching a barrier layer for pressure application, and stretching the preform into an optical fiber with multiple openings. An extrusion die comprising an additive manufactured material, having a proximal side having openings and having a distal side having openings, wherein the openings of the proximal side are of feed channels, wherein the openings of the distal side are of forming channels, and wherein in side the body of the die, two of the feed channels combine the forming channels.