Basic Shapes¶

Utility functions for creating and manipulating basic 3D shapes and geometric calculations. These functions extend build123d's capabilities with shapes and operations commonly used in 3D design.

Geometric Calculation¶

adjacent_length¶

Calculates the adjacent side length of a right triangle given the angle and opposite side length.

apothem_to_radius¶

Arguments - apothem (float): The apothem of the polygon - side_count (int): The number of sides of the poygon.

circular_intersection¶

calculates the circumradius of a regular polygon given its apothem

Finds the intersection point along one axis given a coordinate on the other axis of a circle's perimeter.

Raises: - ValueError: If coordinate is greater than radius or negative

distance_to_circle_edge¶

Calculates the distance from a given point to the edge of a circle in a specified direction.

Raises: - ValueError: If the ray does not meet the circle at all

opposite_length¶

Calculates the opposite side length of a right triangle given the angle and adjacent side length.

radius_to_apothem¶

Part Classes¶

DiamondCylinder¶

Part Object: DiamondCylinder

Creates an extruded diamond (4-sided polygon) that behaves like a cylinder. This is a convenience wrapper for PolygonalCylinder with 4 sides.

Arc Size Behavior: - arc_size=360 produces the full diamond profile - arc_size<360 clips the XY profile and reduces volume while preserving Z behavior from height and stretch[2]

DiamondTorus¶

Part Object: DiamondTorus

Creates a torus by sweeping a diamond (square rotated 45°) along a circular path.

    or MAX of object. Defaults to (Align.CENTER, Align.CENTER, Align.CENTER)

mode (Mode, optional): combine mode. Defaults to Mode.ADD

PolygonalCylinder¶

Part Object: PolygonalCylinder

Creates an extruded regular polygon that behaves like a cylinder.

Arc Size Behavior: - arc_size=360 keeps the full regular polygonal profile - arc_size<360 clips the XY profile and reduces volume while preserving Z behavior from height and stretch[2]

RoundedCylinder¶

Part Object: RoundedCylinder

Creates a cylinder with rounded (filleted) top and bottom edges.

    or MAX of object. Defaults to (Align.CENTER, Align.CENTER, Align.CENTER)

mode (Mode, optional): combine mode. Defaults to Mode.ADD

Raises: - ValueError: If height is not greater than radius * 2

TeardropCylinder¶

Part Object: TeardropCylinder

Creates a 3D teardrop-shaped cylinder by extruding a teardrop sketch. Particularly useful for creating holes that print well on FDM printers without supports.

Teardrop¶

Sketch Object: Teardrop

Creates a 2D teardrop-shaped sketch. The shape is useful for 3D printing holes that minimize overhangs.

    or MAX of object. Defaults to (Align.CENTER, Align.CENTER)

mode (Mode, optional): combine mode. Defaults to Mode.ADD

Examples¶

from build123d import BuildPart, Mode
from b3dkit import (
    DiamondTorus,
    RoundedCylinder,
    TeardropCylinder,
    adjacent_length,
    opposite_length,
)

# A cylinder with rounded ends
rounded_cyl = RoundedCylinder(radius=10, height=30)

# A torus swept from a diamond profile
torus = DiamondTorus(major_radius=20, minor_radius=3)

# A teardrop hole, which prints without support when the axis is horizontal
with BuildPart() as part:
    RoundedCylinder(radius=5, height=30)   # height must exceed radius * 2
    TeardropCylinder(
        radius=5,
        peak_distance=6,
        height=15,
        mode=Mode.SUBTRACT,
    )

# Right-triangle helpers, useful when laying out tapers
opp = opposite_length(30, 10)   # 30 degree angle, adjacent side of 10
adj = adjacent_length(45, 5)    # 45 degree angle, opposite side of 5