Dielectrophoresis-assisted (DEP) on-demand printing of dielectric-liquid-based colloidal gold under room conditions is demonstrated and employed to print 2D and 3D structures with sub-micrometer feature sizes. The focus of the work is primarily on explaining the physics of the printing process, based on the formation of a controlled sequence of sub-micrometer drops. The physics of 3D structure formation on the substrate is explained through the visualization and analysis of various time-scales relevant to the printing process and the pinning of the contact line of the printed colloids. A parametric variation of the related variables, namely the applied voltage and the pulse length, is used to investigate the morphology and topography of a host of basic, printable 2D and 3D features. It is established that it is possible to obtain uniform particle deposits in 2D by filling up an initial coffee-ring-type non-uniform deposit with a series of subsequently formed drops, all obtained during a single electric pulse. Finally, on-demand production of multilayered, sub-micrometer gold tracks is demonstrated, where the annealed tracks exhibit exceptionally low electrical resistivity for their sizes, only two times higher than that of bulk gold.