As the material is polymerizing, it undergoes an increase in density relative to the pre-cure material, causing sedimentation, which in turn causes the edges to resist movement due to the boundary regions established by the vial geometry. There are also likely convection effects due to exothermic reaction of the polymerization . In comparison, the addition of non-crosslinked alginate as a secondary, viscosity modulating additive, at a final concentration of 0.5 wt.% dramatically improves the printability of this PEGDA platform due to reduced sedimentation occurring, as seen with the gyroid structural example in Figure . This modulated resin with PEGDA and alginate does not show any of the printing artifacts displayed for pure PEGDA resins. This difference in shape fidelity is directly attributed to the shift in viscosity. The materials selected here create a semi-interpenetrating network in the resulting structure, as the alginate chains do not covalently bond to the PEGDA network, nor do they crosslink themselves .