CSM density profiles for a binary system with an 18 M_⊙ donor and a 16.2 M_⊙ companion, constructed from the mass-loss history shown in Figure 3. The left panel shows the full radial extent of the CSM, while the right panel zooms in on the inner region relevant to interacting SNe. The gray shaded region at r ≲ 3 × 10¹⁴ cm indicates the approximate binary orbital separation; regions within this radius are excluded from the CSM profile. Compared to the noninteracting case, binary interactions produce denser and more structured CSM, including shell-like features during RLOF.