Concentrated colloidal gels have been utilized as inks for the direct-write assembly of complex 3D architectures. However, such inks undergo a “jamming transition” when deposited through cylindrical nozzles with diameters on the order of 100 mm or less. To overcome such difficulties, we are exploring a new ink design based on mixtures of attractive and repulsive colloidal particles. Specifically, these biphasic inks are composed of silica microspheres coated with either a cationic polyelectrolyte or a comb polymer consisting of a cationic backbone and charge neutral polyethylene oxide teeth. Upon adding salt to this system, the cationic polyelectrolyte-coated silica microspheres spontaneously flocculate while the comb polymer-coated colloids remain fully stabilized. Using confocal microcsopy, we have directly imaged the 3D structural evolution of such mixtures as a function of total microsphere volume fraction, ratio of attractive-to-repulsive microspheres, and salt concentration. Experiments are now underway to characterize the structural evolution of ink filaments patterned by direct ink writing.