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Shape Builder

In one sentence: Compose new Part shapes by combining existing vertices, edges, wires, faces, and shells — building up from lower-level topological elements to higher-level ones.

Overview

Workbench: Part · Menu: Part → Shape Builder
Toolbar: Part Tools · Shortcut: none

Shape Builder opens a dialog that lets you create higher-level OCCT topology from lower-level elements. You can build an edge from two vertices, a wire from edges, a face from wires, a shell from faces, or a solid from shells — one step up the B-rep topology ladder at a time.

Intuition

FreeCAD's B-rep (boundary representation) topology has a strict hierarchy:

Vertex → Edge → Wire → Face → Shell → Solid → Compound

Sometimes imported geometry arrives with gaps or missing topology: you have faces but no shell, or edges but no wire. Shape Builder lets you explicitly assemble the missing higher-level topology from the lower-level pieces you already have.

This is a power-user tool. For routine modelling, use Extrude, Loft, or Face from Wires instead.

When to use it

  • Repairing imported STEP/IGES that has disconnected faces: select all faces and build a Shell, then a Solid.
  • Creating custom wires from individual edges for use as sweep spines.
  • Building compound shapes from manually positioned elements.

When NOT to use it

Available constructions

Mode Input Output Use case
Edge from two vertices 2 vertices 1 edge Connect two points with a straight line
Wire from edges N edges (connected) 1 wire Assemble a closed or open path from individual edges
Face from wires 1+ closed wires 1 face Turn wire outlines into a planar face
Shell from faces N faces 1 shell Group faces into an open or closed shell
Solid from shell 1 closed shell 1 solid Close a shell into a watertight solid
Compound from shapes N shapes (any type) 1 compound Group arbitrary shapes without merging

Step-by-step walkthrough

Building a solid from imported faces

  1. Import a STEP file that arrives as disconnected faces.
  2. Part → Shape Builder.
  3. In the dialog, select Shell from Faces.
  4. Click all the faces in the viewport (or use Ctrl+A if all are desired).
  5. Click Create — a shell object appears.
  6. Change the mode to Solid from Shell.
  7. Select the newly created shell.
  8. Click Create — a solid appears.
  9. Use Check Geometry to verify it is valid.

Building a wire from edges

  1. Create or import several edges that share endpoints.
  2. Part → Shape Builder.
  3. Select Wire from Edges.
  4. Click each edge in order.
  5. Click Create — a wire object appears.
  6. Use the wire as a sweep spine with Sweep.

Common mistakes and pitfalls

Shell from Faces requires no gaps

The shell construction succeeds only when all selected faces share edges without gaps. Even a small gap causes OCCT to reject the shell. Use Check Geometry to detect gaps.

Solid from Shell requires a closed shell

An open shell (with boundary edges) cannot become a solid. Close all openings with additional faces before converting to solid.

Python API

import FreeCAD as App
import Part

doc = App.newDocument()

# Build a wire from two edges
v1 = Part.Vertex(0, 0, 0)
v2 = Part.Vertex(10, 0, 0)
v3 = Part.Vertex(10, 10, 0)
v4 = Part.Vertex(0, 10, 0)

e1 = Part.makeLine(v1.Point, v2.Point)
e2 = Part.makeLine(v2.Point, v3.Point)
e3 = Part.makeLine(v3.Point, v4.Point)
e4 = Part.makeLine(v4.Point, v1.Point)

wire = Part.Wire([e1, e2, e3, e4])
face = Part.Face(wire)
shell = Part.Shell([face])

# Add top face and bottom face to close the shell...
# (simplified: just show the wire/face approach)
Part.show(face)
doc.recompute()

# Extrude the face to get a solid
solid = face.extrude(App.Vector(0, 0, 5))
feature = doc.addObject("Part::Feature", "ExtrudedBox")
feature.Shape = solid
doc.recompute()

See also