FreeCAD Scripts
Expert skill for generating production-quality Python scripts for the FreeCAD CAD application. Interprets shorthand, quasi-code, and natural language descriptions of 3D modeling tasks and translates them into correct FreeCAD Python API calls.
When to Use This Skill
- Writing Python scripts for FreeCAD's built-in console or macro system
- Creating or manipulating 3D geometry (Part, Mesh, Sketcher, Path, FEM)
- Building parametric FeaturePython objects with custom properties
- Developing GUI tools using PySide/Qt within FreeCAD
- Manipulating the Coin3D scenegraph via Pivy
- Creating custom workbenches or Gui Commands
- Automating repetitive CAD operations with macros
- Converting between mesh and solid representations
- Scripting FEM analyses, raytracing, or drawing exports
Prerequisites
- FreeCAD installed (0.19+ recommended; 0.21+/1.0+ for latest API)
- Python 3.x (bundled with FreeCAD)
- For GUI work: PySide2 (bundled with FreeCAD)
- For scenegraph: Pivy (bundled with FreeCAD)
FreeCAD Python Environment
FreeCAD embeds a Python interpreter. Scripts run in an environment where these key modules are available:
import FreeCAD # Core module (also aliased as 'App')
import FreeCADGui # GUI module (also aliased as 'Gui') — only in GUI mode
import Part # Part workbench — BRep/OpenCASCADE shapes
import Mesh # Mesh workbench — triangulated meshes
import Sketcher # Sketcher workbench — 2D constrained sketches
import Draft # Draft workbench — 2D drawing tools
import Arch # Arch/BIM workbench
import Path # Path/CAM workbench
import FEM # FEM workbench
import TechDraw # TechDraw workbench (replaces Drawing)
import BOPTools # Boolean operations
import CompoundTools # Compound shape utilitiesThe FreeCAD Document Model
# Create or access a document
doc = FreeCAD.newDocument("MyDoc")
doc = FreeCAD.ActiveDocument
# Add objects
box = doc.addObject("Part::Box", "MyBox")
box.Length = 10.0
box.Width = 10.0
box.Height = 10.0
# Recompute
doc.recompute()
# Access objects
obj = doc.getObject("MyBox")
obj = doc.MyBox # Attribute access also works
# Remove objects
doc.removeObject("MyBox")Core Concepts
Vectors and Placements
import FreeCAD
# Vectors
v1 = FreeCAD.Vector(1, 0, 0)
v2 = FreeCAD.Vector(0, 1, 0)
v3 = v1.cross(v2) # Cross product
d = v1.dot(v2) # Dot product
v4 = v1 + v2 # Addition
length = v1.Length # Magnitude
v_norm = FreeCAD.Vector(v1)
v_norm.normalize() # In-place normalize
# Rotations
rot = FreeCAD.Rotation(FreeCAD.Vector(0, 0, 1), 45) # axis, angle(deg)
rot = FreeCAD.Rotation(0, 0, 45) # Euler angles (yaw, pitch, roll)
# Placements (position + orientation)
placement = FreeCAD.Placement(
FreeCAD.Vector(10, 20, 0), # translation
FreeCAD.Rotation(0, 0, 45), # rotation
FreeCAD.Vector(0, 0, 0) # center of rotation
)
obj.Placement = placement
# Matrix (4x4 transformation)
import math
mat = FreeCAD.Matrix()
mat.move(FreeCAD.Vector(10, 0, 0))
mat.rotateZ(math.radians(45))Creating and Manipulating Geometry (Part Module)
The Part module wraps OpenCASCADE and provides BRep solid modeling:
import FreeCAD
import Part
# --- Primitive Shapes ---
box = Part.makeBox(10, 10, 10) # length, width, height
cyl = Part.makeCylinder(5, 20) # radius, height
sphere = Part.makeSphere(10) # radius
cone = Part.makeCone(5, 2, 10) # r1, r2, height
torus = Part.makeTorus(10, 2) # major_r, minor_r
# --- Wires and Edges ---
edge1 = Part.makeLine((0, 0, 0), (10, 0, 0))
edge2 = Part.makeLine((10, 0, 0), (10, 10, 0))
edge3 = Part.makeLine((10, 10, 0), (0, 0, 0))
wire = Part.Wire([edge1, edge2, edge3])
# Circles and arcs
circle = Part.makeCircle(5) # radius
arc = Part.makeCircle(5, FreeCAD.Vector(0, 0, 0),
FreeCAD.Vector(0, 0, 1), 0, 180) # start/end angle
# --- Faces ---
face = Part.Face(wire) # From a closed wire
# --- Solids from Faces/Wires ---
extrusion = face.extrude(FreeCAD.Vector(0, 0, 10)) # Extrude
revolved = face.revolve(FreeCAD.Vector(0, 0, 0),
FreeCAD.Vector(0, 0, 1), 360) # Revolve
# --- Boolean Operations ---
fused = box.fuse(cyl) # Union
cut = box.cut(cyl) # Subtraction
common = box.common(cyl) # Intersection
fused_clean = fused.removeSplitter() # Clean up seams
# --- Fillets and Chamfers ---
filleted = box.makeFillet(1.0, box.Edges) # radius, edges
chamfered = box.makeChamfer(1.0, box.Edges) # dist, edges
# --- Loft and Sweep ---
loft = Part.makeLoft([wire1, wire2], True) # wires, solid
swept = Part.Wire([path_edge]).makePipeShell([profile_wire],
True, False) # solid, frenet
# --- BSpline Curves ---
from FreeCAD import Vector
points = [Vector(0,0,0), Vector(1,2,0), Vector(3,1,0), Vector(4,3,0)]
bspline = Part.BSplineCurve()
bspline.interpolate(points)
edge = bspline.toShape()
# --- Show in document ---
Part.show(box, "MyBox") # Quick display (adds to active doc)
# Or explicitly:
doc = FreeCAD.ActiveDocument or FreeCAD.newDocument()
obj = doc.addObject("Part::Feature", "MyShape")
obj.Shape = box
doc.recompute()Topological Exploration
shape = obj.Shape
# Access sub-elements
shape.Vertexes # List of Vertex objects
shape.Edges # List of Edge objects
shape.Wires # List of Wire objects
shape.Faces # List of Face objects
shape.Shells # List of Shell objects
shape.Solids # List of Solid objects
# Bounding box
bb = shape.BoundBox
print(bb.XMin, bb.XMax, bb.YMin, bb.YMax, bb.ZMin, bb.ZMax)
print(bb.Center)
# Properties
shape.Volume
shape.Area
shape.Length # For edges/wires
face.Surface # Underlying geometric surface
edge.Curve # Underlying geometric curve
# Shape type
shape.ShapeType # "Solid", "Shell", "Face", "Wire", "Edge", "Vertex", "Compound"Mesh Module
import Mesh
# Create mesh from vertices and facets
mesh = Mesh.Mesh()
mesh.addFacet(
0.0, 0.0, 0.0, # vertex 1
1.0, 0.0, 0.0, # vertex 2
0.0, 1.0, 0.0 # vertex 3
)
# Import/Export
mesh = Mesh.Mesh("/path/to/file.stl")
mesh.write("/path/to/output.stl")
# Convert Part shape to Mesh
import Part
import MeshPart
shape = Part.makeBox(1, 1, 1)
mesh = MeshPart.meshFromShape(Shape=shape, LinearDeflection=0.1,
AngularDeflection=0.5)
# Convert Mesh to Part shape
shape = Part.Shape()
shape.makeShapeFromMesh(mesh.Topology, 0.05) # tolerance
solid = Part.makeSolid(shape)Sketcher Module
Create a sketch on XY plane
sketch = doc.addObject("Sketcher::SketchObject", "MySketch") sketch.Placement = FreeCAD.Placement( FreeCAD.Vector(0, 0, 0), FreeCAD.Rotation(0, 0, 0, 1) )
Add geometry (returns geometry index)
idx_line = sketch.addGeometry(Part.LineSegment( FreeCAD.Vector(0, 0, 0), FreeCAD.Vector(10, 0, 0))) idx_circle = sketch.addGeometry(Part.Circle( FreeCAD.Vector(5, 5, 0), FreeCAD.Vector(0, 0, 1), 3))
Add constraints
sketch.addConstraint(Sketcher.Constraint("Coincident", 0, 2, 1, 1)) sketch.addConstraint(Sketcher.Constraint("Horizontal", 0)) sketch.addConstraint(Sketcher.Constraint("DistanceX", 0, 1, 0, 2, 10.0)) sketch.addConstraint(Sketcher.Constraint("Radius", 1, 3.0)) sketch.addConstraint(Sketcher.Constraint("Fixed", 0, 1))
Constraint types: Coincident, Horizontal, Vertical, Parallel, Perpendicular,
Tangent, Equal, Symmetric, Distance, DistanceX, DistanceY, Radius, Angle,
Fixed (Block), InternalAlignment
doc.recompute()
### Draft Module
import Draft import FreeCAD
2D shapes
line = Draft.makeLine(FreeCAD.Vector(0,0,0), FreeCAD.Vector(10,0,0)) circle = Draft.makeCircle(5) rect = Draft.makeRectangle(10, 5) poly = Draft.makePolygon(6, radius=5) # hexagon
Operations
moved = Draft.move(obj, FreeCAD.Vector(10, 0, 0), copy=True) rotated = Draft.rotate(obj, 45, FreeCAD.Vector(0,0,0), axis=FreeCAD.Vector(0,0,1), copy=True) scaled = Draft.scale(obj, FreeCAD.Vector(2,2,2), center=FreeCAD.Vector(0,0,0), copy=True) offset = Draft.offset(obj, FreeCAD.Vector(1,0,0)) array = Draft.makeArray(obj, FreeCAD.Vector(15,0,0), FreeCAD.Vector(0,15,0), 3, 3)
## Creating Parametric Objects (FeaturePython)
FeaturePython objects are custom parametric objects with properties that trigger recomputation:
import FreeCAD import Part
class MyBox: """A custom parametric box."""
def __init__(self, obj): obj.Proxy = self obj.addProperty("App::PropertyLength", "Length", "Dimensions", "Box length").Length = 10.0 obj.addProperty("App::PropertyLength", "Width", "Dimensions", "Box width").Width = 10.0 obj.addProperty("App::PropertyLength", "Height", "Dimensions", "Box height").Height = 10.0
def execute(self, obj): """Called on document recompute.""" obj.Shape = Part.makeBox(obj.Length, obj.Width, obj.Height)
def onChanged(self, obj, prop): """Called when a property changes.""" pass
def __getstate__(self): return None
def __setstate__(self, state): return None
class ViewProviderMyBox: """View provider for custom icon and display settings."""
def __init__(self, vobj): vobj.Proxy = self
def getIcon(self): return ":/icons/Part_Box.svg"
def attach(self, vobj): self.Object = vobj.Object
def updateData(self, obj, prop): pass
def onChanged(self, vobj, prop): pass
def __getstate__(self): return None
def __setstate__(self, state): return None
--- Usage ---
doc = FreeCAD.ActiveDocument or FreeCAD.newDocument("Test") obj = doc.addObject("Part::FeaturePython", "CustomBox") MyBox(obj) ViewProviderMyBox(obj.ViewObject) doc.recompute()
### Common Property Types
| Property Type | Python Type | Description |
|---|---|---|
| `App::PropertyBool` | `bool` | Boolean |
| `App::PropertyInteger` | `int` | Integer |
| `App::PropertyFloat` | `float` | Float |
| `App::PropertyString` | `str` | String |
| `App::PropertyLength` | `float` (units) | Length with units |
| `App::PropertyAngle` | `float` (deg) | Angle in degrees |
| `App::PropertyVector` | `FreeCAD.Vector` | 3D vector |
| `App::PropertyPlacement` | `FreeCAD.Placement` | Position + rotation |
| `App::PropertyLink` | object ref | Link to another object |
| `App::PropertyLinkList` | list of refs | Links to multiple objects |
| `App::PropertyEnumeration` | `list`/`str` | Dropdown selection |
| `App::PropertyFile` | `str` | File path |
| `App::PropertyColor` | `tuple` | RGB color (0.0-1.0) |
| `App::PropertyPythonObject` | any | Serializable Python object |
## Creating GUI Tools
### Gui Commands
import FreeCAD import FreeCADGui
class MyCommand: """A custom toolbar/menu command."""
def GetResources(self): return { "Pixmap": ":/icons/Part_Box.svg", "MenuText": "My Custom Command", "ToolTip": "Creates a custom box", "Accel": "Ctrl+Shift+B" }
def IsActive(self): return FreeCAD.ActiveDocument is not None
def Activated(self):
Command logic here
FreeCAD.Console.PrintMessage("Command activated\n")
FreeCADGui.addCommand("My_CustomCommand", MyCommand())
### PySide Dialogs
from PySide2 import QtWidgets, QtCore, QtGui
class MyDialog(QtWidgets.QDialog): def __init__(self, parent=None): super().__init__(parent or FreeCADGui.getMainWindow()) self.setWindowTitle("My Tool") self.setMinimumWidth(300)
layout = QtWidgets.QVBoxLayout(self)
Input fields
self.label = QtWidgets.QLabel("Length:") self.spinbox = QtWidgets.QDoubleSpinBox() self.spinbox.setRange(0.1, 1000.0) self.spinbox.setValue(10.0) self.spinbox.setSuffix(" mm")
form = QtWidgets.QFormLayout() form.addRow(self.label, self.spinbox) layout.addLayout(form)
Buttons
btn_layout = QtWidgets.QHBoxLayout() self.btn_ok = QtWidgets.QPushButton("OK") self.btn_cancel = QtWidgets.QPushButton("Cancel") btn_layout.addWidget(self.btn_ok) btn_layout.addWidget(self.btn_cancel) layout.addLayout(btn_layout)
self.btn_ok.clicked.connect(self.accept) self.btn_cancel.clicked.connect(self.reject)
Usage
dialog = MyDialog() if dialog.exec_() == QtWidgets.QDialog.Accepted: length = dialog.spinbox.value() FreeCAD.Console.PrintMessage(f"Length: {length}\n")
### Task Panel (Recommended for FreeCAD integration)
class MyTaskPanel: """Task panel shown in the left sidebar."""
def __init__(self): self.form = QtWidgets.QWidget() layout = QtWidgets.QVBoxLayout(self.form) self.spinbox = QtWidgets.QDoubleSpinBox() self.spinbox.setValue(10.0) layout.addWidget(QtWidgets.QLabel("Length:")) layout.addWidget(self.spinbox)
def accept(self):
Called when user clicks OK
length = self.spinbox.value() FreeCAD.Console.PrintMessage(f"Accepted: {length}\n") FreeCADGui.Control.closeDialog() return True
def reject(self): FreeCADGui.Control.closeDialog() return True
def getStandardButtons(self): return int(QtWidgets.QDialogButtonBox.Ok | QtWidgets.QDialogButtonBox.Cancel)
Show the panel
panel = MyTaskPanel() FreeCADGui.Control.showDialog(panel)
## Coin3D Scenegraph (Pivy)
from pivy import coin import FreeCADGui
Access the scenegraph root
sg = FreeCADGui.ActiveDocument.ActiveView.getSceneGraph()
Add a custom separator with a sphere
sep = coin.SoSeparator() mat = coin.SoMaterial() mat.diffuseColor.setValue(1.0, 0.0, 0.0) # Red trans = coin.SoTranslation() trans.translation.setValue(10, 10, 10) sphere = coin.SoSphere() sphere.radius.setValue(2.0) sep.addChild(mat) sep.addChild(trans) sep.addChild(sphere) sg.addChild(sep)
Remove later
sg.removeChild(sep)
## Custom Workbench Creation
import FreeCADGui
class MyWorkbench(FreeCADGui.Workbench): MenuText = "My Workbench" ToolTip = "A custom workbench" Icon = ":/icons/freecad.svg"
def Initialize(self): """Called at workbench activation.""" import MyCommands # Import your command module self.appendToolbar("My Tools", ["My_CustomCommand"]) self.appendMenu("My Menu", ["My_CustomCommand"])
def Activated(self): pass
def Deactivated(self): pass
def GetClassName(self): return "Gui::PythonWorkbench"
FreeCADGui.addWorkbench(MyWorkbench)
## Macro Best Practices
Standard macro header
-- coding: utf-8 --
FreeCAD Macro: MyMacro
Description: Brief description of what the macro does
Author: YourName
Version: 1.0
Date: 2026-04-07
import FreeCAD import Part from FreeCAD import Base
Guard for GUI availability
if FreeCAD.GuiUp: import FreeCADGui from PySide2 import QtWidgets, QtCore
def main(): doc = FreeCAD.ActiveDocument if doc is None: FreeCAD.Console.PrintError("No active document\n") return
if FreeCAD.GuiUp: sel = FreeCADGui.Selection.getSelection() if not sel: FreeCAD.Console.PrintWarning("No objects selected\n")
... macro logic ...
doc.recompute() FreeCAD.Console.PrintMessage("Macro completed\n")
if __name__ == "__main__": main()
### Selection Handling
Get selected objects
sel = FreeCADGui.Selection.getSelection() # List of objects sel_ex = FreeCADGui.Selection.getSelectionEx() # Extended (sub-elements)
for selobj in sel_ex: obj = selobj.Object for sub in selobj.SubElementNames: print(f"{obj.Name}.{sub}") shape = obj.getSubObject(sub) # Get sub-shape
Select programmatically
FreeCADGui.Selection.addSelection(doc.MyBox) FreeCADGui.Selection.addSelection(doc.MyBox, "Face1") FreeCADGui.Selection.clearSelection()
### Console Output
FreeCAD.Console.PrintMessage("Info message\n") FreeCAD.Console.PrintWarning("Warning message\n") FreeCAD.Console.PrintError("Error message\n") FreeCAD.Console.PrintLog("Debug/log message\n")
## Common Patterns
### Parametric Pad from Sketch
doc = FreeCAD.ActiveDocument
Create sketch
sketch = doc.addObject("Sketcher::SketchObject", "Sketch") sketch.addGeometry(Part.LineSegment(FreeCAD.Vector(0,0,0), FreeCAD.Vector(10,0,0))) sketch.addGeometry(Part.LineSegment(FreeCAD.Vector(10,0,0), FreeCAD.Vector(10,10,0))) sketch.addGeometry(Part.LineSegment(FreeCAD.Vector(10,10,0), FreeCAD.Vector(0,10,0))) sketch.addGeometry(Part.LineSegment(FreeCAD.Vector(0,10,0), FreeCAD.Vector(0,0,0)))
Close with coincident constraints
for i in range(3): sketch.addConstraint(Sketcher.Constraint("Coincident", i, 2, i+1, 1)) sketch.addConstraint(Sketcher.Constraint("Coincident", 3, 2, 0, 1))
Pad (PartDesign)
pad = doc.addObject("PartDesign::Pad", "Pad") pad.Profile = sketch pad.Length = 5.0 sketch.Visibility = False doc.recompute()
### Export Shapes
STEP export
Part.export([doc.MyBox], "/path/to/output.step")
STL export (mesh)
import Mesh Mesh.export([doc.MyBox], "/path/to/output.stl")
IGES export
Part.export([doc.MyBox], "/path/to/output.iges")
Multiple formats via importlib
import importlib importlib.import_module("importOBJ").export([doc.MyBox], "/path/to/output.obj")
### Units and Quantities
FreeCAD uses mm internally
q = FreeCAD.Units.Quantity("10 mm") q_inch = FreeCAD.Units.Quantity("1 in") print(q_inch.getValueAs("mm")) # 25.4
Parse user input with units
q = FreeCAD.Units.parseQuantity("2.5 in") value_mm = float(q) # Value in mm (internal unit)
## Compensation Rules (Quasi-Coder Integration)
When interpreting shorthand or quasi-code for FreeCAD scripts:
1. **Terminology mapping**: "box" → `Part.makeBox()`, "cylinder" → `Part.makeCylinder()`, "sphere" → `Part.makeSphere()`, "merge/combine/join" → `.fuse()`, "subtract/cut/remove" → `.cut()`, "intersect" → `.common()`, "round edges/fillet" → `.makeFillet()`, "bevel/chamfer" → `.makeChamfer()`
2. **Implicit document**: If no document handling is mentioned, wrap in standard `doc = FreeCAD.ActiveDocument or FreeCAD.newDocument()`
3. **Units assumption**: Default to millimeters unless stated otherwise
4. **Recompute**: Always call `doc.recompute()` after modifications
5. **GUI guard**: Wrap GUI-dependent code in `if FreeCAD.GuiUp:` when the script may run headless
6. **Part.show()**: Use `Part.show(shape, "Name")` for quick display, or `doc.addObject("Part::Feature", "Name")` for named persistent objects
## References
### Primary Links
- [Writing Python code](https://wiki.freecad.org/Manual:A_gentle_introduction#Writing_Python_code)
- [Manipulating FreeCAD objects](https://wiki.freecad.org/Manual:A_gentle_introduction#Manipulating_FreeCAD_objects)
- [Vectors and Placements](https://wiki.freecad.org/Manual:A_gentle_introduction#Vectors_and_Placements)
- [Creating and manipulating geometry](https://wiki.freecad.org/Manual:Creating_and_manipulating_geometry)
- [Creating parametric objects](https://wiki.freecad.org/Manual:Creating_parametric_objects)
- [Creating interface tools](https://wiki.freecad.org/Manual:Creating_interface_tools)
- [Python](https://en.wikipedia.org/wiki/Python_%28programming_language%29)
- [Introduction to Python](https://wiki.freecad.org/Introduction_to_Python)
- [Python scripting tutorial](https://wiki.freecad.org/Python_scripting_tutorial)
- [FreeCAD scripting basics](https://wiki.freecad.org/FreeCAD_Scripting_Basics)
- [Gui Command](https://wiki.freecad.org/Gui_Command)
### Bundled Reference Documents
See the [references/](references/) directory for topic-organized guides:
1. [scripting-fundamentals.md](references/scripting-fundamentals.md) — Core scripting, document model, console
2. [geometry-and-shapes.md](references/geometry-and-shapes.md) — Part, Mesh, Sketcher, topology
3. [parametric-objects.md](references/parametric-objects.md) — FeaturePython, properties, scripted objects
4. [gui-and-interface.md](references/gui-and-interface.md) — PySide, dialogs, task panels, Coin3D
5. [workbenches-and-advanced.md](references/workbenches-and-advanced.md) — Workbenches, macros, FEM, Path, recipes
