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    • Boolean union
    • Boolean difference
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Modeling tools
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  4. Boolean union

Boolean union

Combine overlapping mesh volumes with Boolean Union. Inspect the resulting boundary and internal surfaces.

Before you start

Select two or more editable mesh objects in Object Mode. Apply active modifiers before using the Boolean tool, and use clean closed volumes for a dependable solid result.

Use the operation

Combine intersecting volumes into one Boolean result.

  1. Position the meshes so their overlap matches the intended combined shape. Keep a duplicate if you will need the original operands later.
  2. Select the meshes, open Boolean in the modeling sidebar, and choose Union.
  3. Inspect the new surface around intersections and check the resulting material.

Controls and choices

ControlsWhat changes
Union versus JoinUnion computes a combined volume. Join places geometry in one object without removing internal intersections.
OverlapA small genuine overlap is easier to reason about than faces that only touch exactly. Disconnected inputs may remain separate islands.
MaterialThe Boolean result uses a material derived from the first operand. Do not assume every input material assignment is preserved.

Try it in your scene

Overlap two simple closed meshes and apply Union. Check the silhouette and the former overlap region.

Check the result

Check for an intact exterior and unintended seams. A successful operation is not a guarantee of animation-ready edge flow; inspect topology before further deformation.

Related operations

Boolean differenceBoolean intersectionJoin meshesRecalculate normals

Practice in Show3D

Open the editor and follow the steps with your own scene.
Open Show3DBrowse documentation

On this page

Before you startUse the operationControls and choicesTry it in your sceneCheck the resultRelated operations