Draft = asin(front normal · pull): 0° is parallel to withdrawal; negative means a local undercut. Front means the optical front, even for two-sided mirrors. This checks one pull direction, not global trapping.

Curvature uses the exact surface equations, sampled at patch centres and vertices. H = (k₁+k₂)/2, K = k₁k₂; outward sphere: k = −1/R. Physical feature = aperture width or smaller positive seam step, in mm. The existing feature warning concerns optical blur on the target.

Seams are estimated between nearby boundaries of the same group and interaction, within 2% of the smaller facet width and half a facet width in separation. F5 uses its known ring/sector neighbors and nominal shell seams. Heights are measured along pull. Unmatched seams are unknown; this scene has no wall thickness or closed mould.

Typical starting draft: 1–3°. Protolabs suggests 1–2° for most situations and 3° for light texture. Default warning: 2°; adjust for material, depth and finish.