Function make_thick_solid 

pub fn make_thick_solid(
    model: &mut Model,
    solid: &Shape,
    removed: &[Shape],
    thickness: f64,
    tol: Tolerances,
) -> OgeomResult<Built>

Hollow a solid into a shell of the given wall thickness, opening it at the removed faces.

Two constructions, chosen by the opening’s neighbours. When a removed face meets every neighbour across a corner, the cavity is the inward offset of every kept face with the removed faces left in place, subtracted through the boolean; the flush faces melt away, which is what opens the shell. When a removed face has a tangent neighbour (a blend melting into the face it rounds), leaving it in place would tear the shared vertices, so instead the whole solid offsets inward and each removed face’s cavity image extrudes back out through the opening; the rim a tangent opening leaves is the tapering strip a true constant-thickness wall has there, which is correct rather than a defect.

Errors

As offset_shape, and additionally if thickness is not a usable length, a removed face is not a face of solid, or a tangent opening is not planar.