A printing method for use in fabrication of an electronic unit comprising one or more lines of a regularly repeating structural feature formed over a substrate, the structural feature repeating over a regular interval along each line. The method comprises: using a first print-head arrangement to print portions of a composition at a first pitch along each of the lines; and using a second print-head arrangement to print portions of the composition at a second pitch along each of the lines; such that the first and second pitches together produce a beating pattern along each of the lines, having a beating wavelength matched to the interval of the regularly repeating structural feature.