Using 0.5 wt.% non-crosslinked alginate as a viscosity modifier, the physical properties of aqueous solutions of PEGDA are greatly improved for VAM applications. Figure shows the photopolymer precursor platform investigated here, composed of PEGDA with an average molecular weight of 250 g/mol (PEGDA250) and 700 g/mol (PEGDA700) at a 1:3 weight ratio, alginate, and lithium phenyl-2,4,6trimethylbenzoylphosphinate (LAP). With the addition of non-crosslinked alginate (Mn = ~300,000 g/mol) , the viscosity of the aqueous PEGDA solution is increased (Figure ). The enhanced viscosity of the precursor solution following 0.5wt% alginate addition prevents the forming PEGDA structure from diffusing away during the ~30 s crosslinking period as the full object is forming using VAM (Figure ). Investigation of printability using a "gazebo" construct as a proof-of-principle confirms the enhanced shape fidelity with 15wt% PEGDA and 0.5wt% alginate as compared to lower wt.% PEGDA formulations (Figure ). Supporting Video S1 and Supporting Video S2 show the formation of gyroids and the gazebo shapes, respectively.