Directly before cell rolling, the rods were coated with gelatin or a hydrogel. The coating mold was assembled and disassembled under sterile conditions using forceps. With one mold, four rods could be coated simultaneously. After assembling of the mold, the coating material was directly injected into the mold using a syringe. To avoid movements of the rod during the injection of the coating material, the rods were held in place using forceps. After the coating material was cured, the mold was disassembled and the cannulas were removed. Subsequently, the coated rods were placed into a 3D printed incubation chamber filled with a cBSA solution to enhance cell adhesion.