Spheroids were arranged in a 3 × 3 grid in a lamination layer using a Regenova bio 3D printer and were circular-cultured for 6 days. Spheroids fused together, vascular endothelium cells (green) formed a vascular network in intestinal fibroblasts, and metastatic rectal cancer cells (red) grafted to the spheroids also moved. In the yellow parts, cancer cells invaded into blood vessels.