  Turbulent states are ubiquitous in plasmas and the understanding of
turbulence is fundamental in modern astrophysics. Numerical simulations, which
are the state-of-the-art approach to the study of turbulence, require
substantial computing resources. Recently, attention shifted to methods for
generating synthetic turbulent magnetic fields, affordably creating fields with
parameter-controlled characteristic features of turbulence. In this context,
the BxC toolkit was developed and validated against direct numerical
simulations (DNS) of isotropic turbulent magnetic fields. Here, we demonstrate
novel extensions of BxC to generate realistic turbulent magnetic fields in a
fast, controlled, geometric approach. First, we perform a parameter study to
determine quantitative relations between the BxC input parameters and desired
characteristic features of the turbulent power spectrum, such as the extent of
the inertial range, its spectral slope, and the injection and dissipation
scale. Second, we introduce in the model a set of structured background
magnetic fields B0, as a natural and more realistic extension to the purely
isotropic turbulent fields. Third, we extend the model to include anisotropic
turbulence properties in the generated fields. With all these extensions
combined, our tool can quickly generate any desired structured magnetic field
with controlled, anisotropic turbulent fluctuations, faster by orders of
magnitude with respect to DNSs. These can be used, e.g., to provide initial
conditions for DNS simulations or easily generate synthetic data for many
astrophysical settings, all at otherwise unaffordable resolutions.
