Apparatus for manufacturing a hydrogen 21 line precision measuring device, comprising: a hydrogen 21 line generator, which may be a hydrogen maser, which generates an emission spectrum comprising a spectral line at substantially 1420.40575177 MHz and communicates the spectral line to a frequency counter; which is adapted to receive the spectral line, measures frequency of the spectral line, and communicates an indication of the measured frequency to a computer, which receives the indicated frequency, calculates wavelength of the indicated frequency and communicates control signals to a laser or other marking device to scribe markings on a measuring device substrate at one or more intervals of the calculated wavelength and subdivisions thereof, resulting in the measuring device substrate having a plurality of scribed markings, each pair of the scribed markings at an interval of substantially the calculated wavelength and each of the subdivisions thereof equaling a portion of the calculated wavelength.