SketchUp cleanup tools: Purge, CleanUp³, Solid Inspector² and AI review

Start with what SketchUp already has

SketchUp can clear out a lot on its own, with no extension. Open Window › Model Info, go to Statistics and click Purge Unused. It removes components, materials, tags and styles that nothing in the model uses.

In SketchUp 2025 and newer, SketchUp also asks whether to purge each time you save by hand. You can change that in the General tab of Preferences.

Purging only removes things that are unused. It doesn't touch reversed faces, leftover edges or doubled geometry. For those you need to look at the model itself or use an extension.

Check whether a group is a solid

For 3D printing and the Solid Tools, a group or component has to be a solid: a closed volume with no leaks.

• Right-click the group and choose Entity Info. The top of the panel says whether it's a solid.
• In SketchUp Pro, the Solid Tools (Union, Subtract, Trim, Intersect, Split) are under Tools › Solid Tools and on the Solids toolbar. Outer Shell sits directly in the Tools menu and is also in SketchUp Free.

Entity Info tells you that something isn't a solid. It doesn't tell you why. That's where an inspector helps.

The common cleanup extensions

CleanUp³

A free, open-source extension by ThomThom, listed on the Extension Warehouse for SketchUp 2022 to 2026 on macOS and Windows; it needs ThomThom's TT_Lib² library installed too. It cleans geometry in bulk, on the whole model or a selection. Its options include Purge Unused, Erase Hidden Geometry, Erase Duplicate Faces, Merge Coplanar Faces, Repair Split Edges, Erase Stray Edges, Merge Identical Materials and Remove Edge Materials. Merging faces can respect face normals, materials and UV mapping, and there is an option to smooth edges by angle. To remove only stray edges, untick everything except Erase Stray Edges.

Good for: tidying up imported files and leftovers from Intersect.

Solid Inspector²

A free, open-source extension by ThomThom, listed for SketchUp 2022 to 2026 on macOS and Windows. Open it from the Tools menu with a group or component selected. It marks what stops the object being a solid, such as holes, reversed faces, stray edges, internal faces and nested instances. Tab and Shift+Tab step through the problems, and Fix or Fix All repairs many of them. Open holes, where a surface has a free border, you close by hand. Its listing notes the analysis can be slow on very large models.

Good for: a part that won't print. Use it before Solid Tools or an STL export. See preparing a model for 3D printing.

Solid Tools

Built into SketchUp Pro. These combine and cut solids. They're modelling tools, not cleanup tools, but they only work once the solids are clean.

Skimp

A paid extension from Mind.Sight.Studios that reduces the polygon count of heavy objects, often on import. Useful when a downloaded chair or plant has far more faces than it needs.

Transmutr

A paid importer from Lindalë that cleans up a file as it comes in (scale, materials, polygon count) and can make lightweight proxies for some renderers.

Good for: bringing big third-party models into SketchUp without dragging the whole file down.

All of these work on rules: each finds one kind of problem and fixes it the same way every time. That's fast and predictable. They won't tell you that a post stops short of the deck.

Where an AI reviewer fits

We make Lookover, so weigh this section accordingly.

Lookover reviews the whole model and lists what's wrong. It runs in two parts.

Automatic checks are fixed rules, like the tools above: faces painted on the back, faces that could be one face, loose edges that look like leftovers, geometry doubled in place, copies that should be components, and materials, tags and components nothing uses. Many have a Fix it button. Others are listed for you to decide, such as copies that should be components, or unused styles, because SketchUp can't undo removing a style.

The AI review reads the model and looks at screenshots of it, then flags things a rule can't judge: a table floating an inch above the floor, or stairs whose risers don't add up to the floor height. Where the fix is clear, it offers one. You can also tell it what to focus on, like “check the stairs”.

A review doesn't change your geometry. The model changes only when you click Fix it, and each fix is one undo step, so Cmd+Z (Ctrl+Z on Windows) puts it back. A fix that deletes something asks first.

Free covers 2 reviews a month; Pro is paid. The AI part runs on our servers, so a review sends a summary of the model's structure (groups, components, tags, materials, their names, counts and sizes) and a few screenshots, not the .skp file. See the privacy policy. A review needs an internet connection and SketchUp 2024 or newer.

Lookover isn't a replacement for CleanUp³ when you want to merge faces across a big import in one pass. It's better for a review before you send a model: one list of what's wrong, with the reason for each.