Examples of hole and ring structures observed in the GM with JWST (De Looze et al. 2024; first row) compared to those produced in run W15-IIb-sh-MHD+dec-rl-hr at two different epochs: 258 years (second row) and 367 years (third row). The latter epoch corresponds approximately to the current age of Cas A. The bottom panels highlight the selected regions within the context of the entire shocked shell; the dashed box indicates the region analyzed in Figs. 6, 8, and 9. Hole dimensions are shown in arcseconds, assuming a distance of 3.4 kpc to Cas A.