Walls are fixed thickness regardless of model size, so small models are
wall-dominated (high material factor) while large models are infill-dominated.
_effective_factor() uses log-linear interpolation:
factor = MATERIAL_FACTOR - log10(volume / 25 cm³) × 0.15
Example curve:
0.5 cm³ → 0.76 1 cm³ → 0.71 10 cm³ → 0.56
26 cm³ → 0.50 100 cm³ → 0.41 500 cm³ → 0.31
MATERIAL_FACTOR env var is now the anchor at 25 cm³ (validated reference).
The card header shows the effective (size-adjusted) factor for the specific job.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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