  Electrochemical 3D printing of conductors with microscale resolution holds a
great promise for a wide range of applications, but the choice of suitable
metals for these technologies remains limited. Most efforts so far have been
focused on deposition of copper, however, other metals are also of interest,
especially when tuning of mechanical, electrical, or optical properties is
required for a given application. Here we address the issue of a limited
materials choice in electrochemical 3D printing by extending the materials
library to silver and nickel. Free-standing microscale structures are
fabricated in a single step via locally confined electrochemical 3D printing
using FluidFM - a microchanneled cantilever nanopipette capable to deliver
electrolyte through sub-microscale opening. The 3D printed structures are
constructed in a layer-by-layer fashion, which allows complex geometrical
shapes such as double rings, helices and pyramids. We report the process
performance in terms of printing speed (in the range 7 - 40 nm s-1 for silver
and 27 - 42 nm s-1 for nickel) and reveal dense inner structure and chemical
purity of the printed features.
