Exemplary fractal dust grains with a number of monomers N_mon. Monomer sizes and N_mon are selected in such a way to guarantee an exact effective radius a_eff. Grains in the same row possess identical radii a_eff while gains in the same column are constructed with the same fractal dimension D_f. The quantity a_out is the radius of the smallest sphere enveloping the entire aggregate. Note that a_eff approaches a_out with increasing D_f. Each grain’s coordinate system (target-frame) {â₁, â₂, â₃} is unambiguously defined by its inertia tensor.