Replace the rectangular cube/wall constructions for the bottom and top shells with `linear_extrude` of a rounded 2D footprint. Outer envelope and interior cavity share the same radius so wall thickness stays uniform (~2 mm) including at the corner diagonals. Seam ledge, lip, and channel ribs are clipped to the rounded outer envelope so they don't protrude past the rounded vertical faces. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>