Ellipsoidal fits to the filaments in simulations with box sizes of L = 3.2 H, L = 1.6 H, and L = 0.8 H. Top panel: mean distance 𝒟 relative to the short axis (circles) and the long axis (plusses). The filaments are very narrow, with a width of only 𝒟_long ≈ 0.01 H relative to the long axis. Their lengths relative to the short axis extend up to 40% of the gas scale height. The number of large filaments in the box with L = 3.2 H is significantly higher than in the smaller box with L = 1.6 H, due to the increased space in the large box. The smallest box with L = 0.8 H boasts two very long filaments, the same number as the box with L = 1.6 H. This could indicate an effect of the periodic boundary conditions along the y-direction, which allow particle structures to connect more easily as they pass the boundary. Lower panel: Angle with the azimuthal y-axis. Large filaments with areas above ~10⁻³ H² have very small angles with the y-axis.