Alternatively, we employed a "dual-macromonomer" strategy to combine the elasticity of high MW PEG and the strength of low MW PEG. A series of resins containing varying ratios of PEGDMA 10k and PEGDA 700 were formulated and printed into hydrogels after swelling in PBS (Figure ). As shown in Figures , PEGDA 700 greatly improved the mechanical strength of the 3D printed hydrogels, with maximal tensile stress up to ~1.5 MPa (Figure ). With 10 wt% of PEGDA 700, the Young's modulus of the hydrogel was about 2.4 MPa, while the elongation at break was ~50%. On the other hand, the compression modulus (Ec) reached 3.2 MPa (Figures and) and the compressive toughness was nearly 1.0 MJ•m -3 , which is 2-4 folds higher than that of single-PEGDMA hydrogels with relatively high elasticity made from PEGDMA 4k-8k (Figure and Table ). The swelling ratio was still high enough to keep the water content at ~75% (Figure ). As a result, the dualmacromonomer hydrogels were stronger and tougher than single-PEGDMA hydrogels (Figure ).