A key aspect of the methods of fabricating of chip-scale atomic clocks developed at NIST over the last two years is the possibility that many devices could be fabricated and assembled simultaneously, leading to a large savings in cost and assembly time. Current atomic frequency references are assembled essentially one-by-one by hand, which is expensive and also leads to significant variations in the output frequency from unit to unit. Since the microfabrication processes used in the NIST devices are based on photolithographic patterning and etching of planar wafers, it is a simple matter to fabricate multiple units with the same process sequence. If units were spaced by 2 mm, over 3000 individual clocks could be made on a single wafer of diameter 150 mm. A schematic showing how such wafer-level assembly might be accomplished for physics packages is shown below.