We report a significant advance in preform extrusion and die design, which has allowed for the first time the fabrication of complex structured preforms using soft glass and polymer billets. Structural preform distortions are minimized by adjustment of the material flow within the die. The low propagation loss of an extruded complex bismuth glass fiber demonstrates the potential of this advanced extrusion technique for the fabrication of novel soft glass and polymer microstructured fiber designs.