1) Researchers are developing a 3D-scaffold mammary tissue model containing a vascular system to study how extracellular matrix (ECM) stiffness affects cell morphology and malignancy. 2) The model is created by 3D printing a carbohydrate structure, coating it with a polymer, and dissolving the carbohydrate while encasing the polymer structure in collagen ECM material along with mammary endothelial cells. 3) This allows the creation of vascular channels within the ECM and enables testing of how varying ECM stiffness affects malignant mammary epithelial cells in a more physiologically relevant 3D environment compared to standard 2D cultures.