  We present a micro-electromechanical system (MEMS) based method for the
resist free patterning of nano-structures. Using a focused ion beam (FIB) to
customize larger MEMS machines, we fabricate apertures as small as 50 nm on
plates that can be moved with nanometer precision over an area greater than
20x20 {\mu}m^2. Depositing thermally evaporated gold atoms though the apertures
while moving the plate results in the deposition of nanoscale metal patterns.
Adding a shutter only microns above the aperture, enables high speed control of
not only where but also when atoms are deposited. Using a shutter, different
sized apertures can be selectively opened and closed for nano-structure
fabrication with features ranging from nano- to micrometers in scale. The
ability to evaporate materials with high precision, and thereby fabricate
circuits and structures in situ, enables new kinds of experiments based on the
interactions of a small number of atoms and eventually even single atoms.
