SketchUp Solid Tools guide: Joining and cutting solid models

SketchUp’s Solid Tools can be used to join, cut, or edit the intersection geometry of groups and components that enclose a volume. SketchUp’s official help documentation, updated on 29 September 2026, explains how to use the tools and the requirements for accessing them. Before starting, models must be recognized as “solid”: a solid must enclose a finite, closed volume, with no open faces or disconnected edges.

Check that your model is solid before you begin

1. Right-click the group or component you want to edit and open Entity Info. The panel shows whether the selection is recognized as a solid. Check the parts to be cut and used as cutters individually before proceeding.

2. If the model is not recognized as solid, check for openings in its faces or disconnected edges. The geometry must meet the solid requirements for Solid Tools operations; for cutting operations such as Subtract and Trim, the two solids are expected to overlap.

3. If you’re having trouble locating an opening, you can look for a third-party extension, as the help documentation suggests, or use Solid Inspector, which is available to paid subscribers.

4. If you need to edit a nested component, explode the parent component to access the nested one. You can recreate the parent component after making your changes.

Checking that a model is solid is the first step in preventing failed operations. The tool cursor may indicate that you haven’t made a valid selection until you hover over a valid solid. Selection order also affects the result of cutting operations, so decide which part is the cutter and which is being cut before clicking.

Which tool should you use?

Outer Shell and Union can produce similar results, but they are not the same operation. Outer Shell leaves only the outer faces, while the result of Union may also contain internal geometry. If it matters whether internal faces remain in the model, choose the tool with this difference in mind.

Access to the tools varies depending on the SketchUp environment and plan you use. According to the official help pages, Outer Shell is available in the free version of SketchUp for Web; the other Solid Tools require a subscription. In SketchUp Pro, the tools are available in the Solids toolbar and under Tools > Solid Tools. In the web version, the Solids toolbar is in the left-hand panel.

Join and cut solids

1. Create an outer shell: In SketchUp Pro, select the intersecting groups or components and choose Outer Shell from the context menu. Alternatively, activate the tool and select the first solid, followed by the others. In the web version, you can start the Outer Shell tool from the left-hand toolbar. The result removes internal geometry and keeps the outer faces. This is useful for simplifying details that won’t be visible.

2. Join solids: Select the Union tool, then click one solid followed by the other solid you want to join to it. Select additional solids if needed. The operation produces a single solid. Because the result may preserve internal geometry, consider Outer Shell instead of Union if you need to keep only the outer faces.

3. Subtract one part from another: Activate Subtract and select the cutting solid first, followed by the solid to be cut. For example, when using one part to make a hole in another, select the cutter first. The cutting model is deleted at the end of the operation. Subtraction won’t work if the parts to be cut don’t overlap.

4. Trim while keeping the cutter: With the Trim tool, select the cutting solid first and the solid to be cut second. Unlike Subtract, Trim leaves the cutting model in the scene. You can move the cutter temporarily to get a better look at the cut surface.

5. Get a subtract-like result in the free web version: In the free version of SketchUp for Web, you can use Intersect Faces > With Model instead of Subtract. First, create two separate volumes and position the cutting shape so that it intersects the shape to be cut. Select the cutting shape and choose the command from the context menu; then erase the unwanted geometry with the Eraser tool. The shapes don’t need to be solid for this method, but it takes more steps than Subtract in Solid Tools.

6. Update component instances: When a component is edited with a Solid Tool, the change may not automatically apply to all instances of that component. Right-click the edited part and choose Make Component; in the creation window, use the name of the original component definition and confirm that you want to replace the definition. This updates other instances that use the same definition.

Using Solid Tools in architectural and visualization workflows

Solid Tools can be used to combine volumes in massing models, create openings in elements, or edit intersecting parts. In context models where only the exterior is needed, Outer Shell can remove internal geometry that won’t be visible. The official documentation notes that this can help lighten the model and improve SketchUp performance. However, the result depends on how much geometry is removed from the model; the same performance improvement cannot be assumed for every file.

For interior and detail modeling, Subtract can remove the cutting part at the end of the operation, while Trim keeps it in the model. Updating the definition is also part of the workflow when working with repeated components. Teams should check which tools are included in their SketchUp plan before getting started; the free version of SketchUp for Web doesn’t include every Solid Tools feature. The source documentation doesn’t specify particular hardware requirements, so it’s not possible to recommend a specific computer threshold.

Common mistakes

• Starting an operation with a model that has open faces or disconnected edges, assuming it is solid.

• Selecting the part to be cut first with Subtract or Trim; the first selection is the cutting solid.

• Assuming Subtract and Trim produce the same result; Subtract removes the cutter, while Trim preserves it.

• Assuming Outer Shell and Union produce the same result in terms of internal geometry.

• Skipping the step to update the component definition so edits apply to other instances.

• Assuming all Solid Tools are available in the free version of SketchUp for Web.