Isosurfaces of the distribution of Fe at the time when the reverse shock starts to interact with the Fe- and Ti-rich plumes of ejecta (upper panels), at the age of Cas A (middle panels), and at t = 2000 yr (lower panels) for different viewing angles (from left to right) for model W15-2-cw-IIb-HD+dec. The opaque irregular isosurfaces correspond to a value of Fe density which is at 5% of the peak density; their colors give the radial velocity in units of 1000 km s⁻¹ on the isosurface (the color coding is defined at the bottom of each panel). The semi-transparent clipped quasi-spherical surfaces indicate the forward (green) and reverse (yellow) shocks. The Earth vantage point lies on the negative y-axis. See online Movie 1foran animation of these data; a navigable 3D graphic of the Fe spatial distribution at the age of Cas A is available at https://skfb.ly/6TKRK.