create the earbud model with build123d

earbud.py

# %%
from typing import Iterable

from build123d import *
from OCP.BRepBuilderAPI import BRepBuilderAPI_Sewing
from OCP.TopAbs import TopAbs_SHELL
from OCP.TopoDS import TopoDS
from ocp_vscode import Camera, set_defaults, show

set_defaults(reset_camera=Camera.CENTER, helper_scale=5, axes=True, axes0=True)

# %%
def get_tangent(u: float, edge: Edge, face: Face):
    """
    Perpendicular to both face norm and edge
    """
    norm = face.normal_at(edge @ u)
    return norm.cross(edge % u)


def sew_faces(faces: Iterable[Face]):
    """
    similar to Shell() but with higher sewing tolerance
    """
    shell_builder = BRepBuilderAPI_Sewing(1e-4)
    for face in faces:
        if face.wrapped is not None:
            shell_builder.Add(face.wrapped)
    shell_builder.Perform()
    shape = shell_builder.SewedShape()
    if shape.ShapeType() != TopAbs_SHELL:
        raise ValueError(f"ShapeType must be TopAbs_SHELL. It is {shape.ShapeType()}")
    return Shell(TopoDS.Shell_s(shape))


"""
ellipse body
"""
body_length = 18
body_width = 8
body_height = 12
open_pos = 8

guide1 = Edge.make_ellipse(
    body_width / 2, body_length / 2, start_angle=-90, end_angle=90, plane=Plane.XY
)
guide2 = Edge.make_ellipse(
    body_length / 2, body_height / 2, end_angle=180, plane=Plane.YZ
)

guide1 = guide1.split(Plane.XZ.offset(open_pos), keep=Keep.BOTTOM)
assert isinstance(guide1, Edge)
guide2 = guide2.split(Plane.XZ.offset(open_pos), keep=Keep.BOTTOM)
assert isinstance(guide2, Edge)

vec10 = guide1 @ 0
vec20 = guide2 @ 1

profile1 = Edge.make_ellipse(abs(vec10.X), abs(vec20.Z), plane=Plane.XZ).translate(
    (0, -open_pos, 0)
)
profile2 = Vector(0, body_length / 2, 0)

profiles = [profile1, profile2]
guides: list[Edge] = [
    guide1,
    guide2,
    guide1.mirror(Plane.YZ),
    guide2.mirror(Plane.XY),
]

face10 = Face.make_gordon_surface(profiles, guides)  # ellipse body


"""
trim ellipse body
"""
loc30 = face10.location_at(0.75, 0.5)
edge30 = Edge.make_ellipse(5, 6).locate(loc30)
wire40 = edge30.project(face10, direction=loc30.z_axis.direction)
assert isinstance(wire40, Wire)

face50 = face10.split(Face.make_surface(wire40))  # body face after trim
assert isinstance(face50, Face)


"""
create base column
"""
edge20 = Edge.make_circle(2).rotate(Axis.Z, -90).translate((8, 5, -4))
face20 = Face.extrude(edge20, (0, 0, -15))  # column face


"""
create transition face
"""
profiles = [edge20, wire40._to_bspline()]

guides = []
for i in range(4):
    u = i / 4
    guides.append(
        Spline(
            profiles[0] @ u,
            profiles[1] @ u,
            tangents=(
                get_tangent(u, profiles[0], face20),
                get_tangent(u, profiles[1], face50),
            ),
        )
    )

face60 = Face.make_gordon_surface(profiles, guides)  # transition face


"""
create final body
"""
faces = [
    face20,
    face50,
    face60,
    Face(Wire(face10.edges().sort_by(Axis.Y)[0])),
    Face(Wire(face20.edges().sort_by(Axis.Z)[0])),
]

shell10 = sew_faces(faces)
solid10 = Solid(shell10)
assert solid10.is_valid

show(solid10)