Here I introduce two papers on direct printing involving droplets.
The first one published in Nature Communications (http://www.nature.com/articles/ncomms1891) reported direct printing of nanostructures by a method involving nanoscale electrohydrodynamic inkjet printing technology. A combination of nanoscopic placement precision, soft-landing fluid dynamics, rapid solvent vapourization, and subsequent self-assembly of the ink colloidal content leads to the formation of nanostructures with base diameters equal to that of a single ejected droplet.
The second one published in Science (http://science.sciencemag.org/content/340/6128/48.full) reported how to build liquid objects by 3-D printers. To create liquid scaffolds, the researchers in University of Oxford custom-built a printer to squirt tiny lipid-coated water droplets from its nozzles and print them onto a platform submerged in an oil bath. Because of their lipid coatings, the tiny droplets formed a very thin bilayer interface instead of fusing to form a larger droplet. The researchers have been able to produce 3-D patterned networks of tens of thousands of connected droplets.