1. A method of creating a guilloché base pattern with two-dimensional periodicity in a plurality of replicate patterns wherein the creating can be assessed in real-time for pattern acceptability by a user, comprising: setting the base pattern in vector space relative to a set of predetermined pattern nodes, the base pattern comprising a spline curve and a hand drawn curve, wherein the spline curve and the hand drawn curve are defined as mathematical entities extending continuously across replicate pattern boundaries; modulating the base pattern by adjusting positions of the pattern nodes for selectively controlling curve shapes of the base pattern; and displaying on an imaging device a guilloché mark comprised of the modulated base pattern and correspondingly modulated replicate patterns contemporaneously with the modulating for user assessment of the mark.