Researchers developed a four axis extrusion-based additive manufacturing system based on fused deposition modeling (FDM) to create tubular hollow scaffolds. With this technique systematic changes in design can be made to alter the mechanical properties for the targeted tissue or organ.
van Kampen, K.A., Olaret, E., Stancu, I.C., Moroni, L. and Mota, C., 2021. Controllable four axis extrusion-based additive manufacturing system for the fabrication of tubular scaffolds with tailorable mechanical properties. Materials Science and Engineering: C, 119, p.111472.