Visualising the field creation process. a) Depicts a set of braided curves (in the form of the pigtail braid) on the left, and a set of twisted curves on the right. b) Depicts the pigtail braid embedded within a sigmoidal tube shape. c) Depicts the embedding of this tube in a Cartesian coordinate system, over the neutral line of a background quadrupolar flux distribution defined at the plane z = 0 (which plays the role of the photosphere in what follows).