Mesh PolyTrim

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Mesh PolyTrim

Menu location
Meshes → Cutting → Trim mesh
Default shortcut
Introduced in version
See also
Mesh PolyCut, Mesh TrimByPlane


The Mesh PolyTrim command trims faces and parts of faces from mesh objects.


  1. During the command the 3D view cannot be changed. It is advisable to properly line up the 3d view first.
  2. Select one or more mesh objects.
  3. There are several ways to invoke the command:
    • Press the Trim mesh button.
    • Select the Meshes → Cutting → Trim mesh option from the menu.
  4. Define a polygon by picking points in the 3D view.
  5. Select an option from the 3D view context menu:
    • Inner: removes the faces and parts of faces that are inside the polygon.
    • Outer: removes the faces and parts of faces that are outside the polygon.
    • Split: removes the faces and parts of faces that are outside the polygon, and creates a new mesh object containing them.
    • Cancel: cancels the command.


See also: FreeCAD Scripting Basics.

To trim a mesh with a polygon use its trim method.

import FreeCAD as App
import Mesh

# Create a non-parametric box-shaped mesh:
msh = App.ActiveDocument.addObject("Mesh::Feature", "Mesh")
msh.Mesh = Mesh.createBox(30, 40, 50)
msh.ViewObject.DisplayMode = "Flat Lines"

# Define some points:
p1 = App.Vector(0, 0, 0)
p2 = App.Vector(60, 0, 0)
p3 = App.Vector(60, 60, 0)

# We need to work on a copy of the msh.Mesh object:
new_msh = msh.Mesh.copy()

# Trim that copy:
new_msh.trim([p1, p2, p3], 0) # 2nd argument: 0=inner, 1=outer.

# Update msh.Mesh:
msh.Mesh = new_msh