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For those who don’t know the tool: Blender is the open-source 3D DCC covering modelling, sculpting, animation, rendering and production tooling; Firg’s Cut Plane sits specifically in its Edit Mode modelling stage, adding an interactive plane-based interface around mesh bisect operations before assets move downstream into UV work, shading, rigging, animation, rendering, 3D print, fabrication or interchange with other DCCs and engines.
Bisect first, regret later
Cut Plane is a Blender extension for an operation that sounds almost aggressively simple: put a plane through a mesh and cut along it – and the interaction model around the cut is amazing. The extension gives Blender’s mesh-editing workflow a positionable plane with a live preview. As the user moves or rotates that plane, Cut Plane recomputes the bisect and redraws the mesh. Pressing Enter commits the operation. Until then, the artist can continue positioning the plane while looking at the actual resulting topology rather than mentally extrapolating where the operation will land.
That preview is a real mesh bisect rather than a visual approximation. The original mesh state is retained during the session and restored when the artist leaves the tool, switches tools, saves the file or exits Edit Mode without committing the operation. That matters in modelling. Cut Plane is not merely drawing a viewport guide over an unchanged object. The preview represents the geometry produced by the current cutting configuration, while the extension manages the original state behind it.
The plane gets Blender manners
Rather than introducing a completely new manipulation scheme, Cut Plane borrows Blender’s normal transform vocabulary. Artists can position the cutting plane through viewport gizmos or use G, R and S. The gizmo supplies movement arrows, three rotation dials plus a view dial and trackball rotation, as well as scale handles.
The workflow stays close to ordinary Edit Mode manipulation. Double-tapping R invokes trackball rotation, while Alt+G, Alt+R and Alt+S clear the respective plane transforms. Escape or right-click cancels the current drag without committing the cut. The plane appears at the mesh centre when the tool starts and immediately displays a preview. Cut Plane is available from the toolbar, the Mesh menu and Blender’s F3 search. The basic workflow is consequently short: invoke it, position the plane, configure the cut and press Enter. That brevity is the point. The extension does not try to replace Blender’s modelling environment with a separate cutting workspace. It makes a familiar operation more inspectable while the artist is deciding where the operation belongs.
Caps, sides and selective surgery
The cutting options cover more than splitting geometry along the plane. Fill caps the resulting cross-section, while Clear Inner and Clear Outer remove geometry on one side of the cutting plane. Changing those settings updates the cut immediately.
For production modelling, Selected Only is particularly useful because it restricts the operation to selected geometry. A plane can therefore pass through a larger object while affecting only the selected component rather than cutting everything it intersects.
That makes Cut Plane applicable to cases where the desired operation is local but a convenient cutting plane necessarily crosses unrelated geometry. The artist can concentrate the operation through selection rather than constructing a plane that somehow avoids every other part of the object.
The workflow is still destructive once committed. Cut Plane’s interactive state exists while the tool is active; pressing Enter commits the resulting mesh operation. It should therefore be understood as a better-controlled modelling operation, not as a permanently parametric construction history.
One plane, now bring friends
Mirror controls expand the operation across the object’s origin. Mirror X, Y and Z create reflected copies of the cutting plane, allowing a single plane to produce two, four or eight corresponding cuts depending on the enabled axes.
Grey ghost planes indicate where those mirrored cuts will occur. Their visibility can be disabled when the viewport becomes too enthusiastic about showing its workings.
This is useful for symmetrical modelling because the artist does not need to position equivalent cutting planes manually. The important reference is the object’s origin, so origin placement becomes part of the operation’s logic rather than an incidental scene detail.
That is also worth checking on imported, duplicated or transformed assets. A mirrored cutting workflow is only as sensible as the coordinate reference it is mirroring around.
Numbers are allowed
Cut Plane supports numeric input during transforms. An artist can type a value while manipulating the plane, with the current input displayed in the header and the plane moving to the specified value. The extension parses Blender scene units, including values such as 0.5m and 25cm, while rotation input uses degrees. That turns the tool from a purely visual cutter into something more appropriate for jobs where a plane must land at a known measurement.
This becomes relevant outside entertainment modelling. Product visualisation, mock-ups and geometry intended for fabrication or 3D printing (Which is ow we found this tool! – stls do ot inherently have a size ;) ) often need a cut to occur at a specific physical location rather than merely somewhere that looks right in perspective view.
Undo has two jobs
The tool maintains its own plane pose history as part of the active operation. According to the developer’s documentation, Ctrl+Z first steps through changes to the plane and then through cuts.
That behaviour is relevant because an interactive cutting operation effectively has two kinds of state: the position and orientation of the cutting instrument, and the resulting topology. Treating plane movement as something that can be revised before falling back to ordinary geometry undo makes the tool feel more like an editing session than a succession of disposable bisect attempts.
The repository also shows that the extension separates several parts of this state management internally. The shipped package contains modules for plane pose and mirror expansion, original-mesh snapshots, selection handling, preview application and restoration, snapping queries, save and load handlers, and tool-scoped pose history.
Extension, not mystery binary
Cut Plane is distributed as a Blender Extension. Installation can be performed by downloading the release ZIP and dragging it into Blender, or through Edit > Preferences > Get Extensions > Install from Disk. The source is published on GitHub, and the project is licensed under GPL-3.0-or-later. That is materially different from merely calling the add-on “free”: the repository supplies an explicit open-source licence governing the code.
For pipeline developers, the repository also documents how to run the extension directly from source in Blender and how to build an extension package. Its test suite runs headlessly against Blender 4.5 and 5.1 in CI.
Where it earns the click
The production advantage is mostly about reducing iteration around an ordinary modelling operation. Without an interactive cutting plane, finding the desired bisect can involve executing a cut, inspecting it, undoing it and adjusting the operation until the result lands where intended. Cut Plane moves much of that decision-making in front of the commit.
Mirroring reduces repetition on symmetrical geometry. Selected Only keeps the plane from indiscriminately operating on everything it crosses. Numeric entry makes measured cuts practical. Snapping provides references to existing topology, and using the original mesh for those snap targets keeps the live preview from undermining its own positioning system.
The tool therefore looks most useful when the exact location of the cut matters. That can include hard-surface modelling, asset preparation, product geometry and fabrication-oriented work. It is less about performing an exotic operation than about making a very ordinary one easier to position, inspect and revise.
There is no reason to turn that into a grander claim. Cut Plane does not need to reinvent mesh modelling to save a few rounds of cut, inspect, swear quietly, undo and repeat.
Small tool, right job
Usually a utility this small would not pop up on the news radar. Cut Plane made the cut (hehehehehe) because we ended up using it ourselves on a 3D-printing project, where we needed to divide geometry cleanly and position the cut precisely. It was simply the right tool at the right moment, which is sometimes a more useful recommendation than another round of feature fireworks.
https://extensions.blender.org/add-ons/cut-plane
https://github.com/firg659-del/cut-plane
| Product | Cut Plane |
| Developer | Firg |
| Version | 1.0.0 |
| Host compatibility | Blender 4.5 or newer |
| Function | Interactive plane-based mesh bisect tool for Blender Edit Mode |
| Cut controls | Fill, Clear Inner, Clear Outer, Selected Only |
| Transform controls | Move, rotate, scale, trackball rotation and numeric input |
| Mirroring | X, Y and Z across the object origin |
| Snapping | Vertices, edge centres, faces and grid |
| Licence | GPL-3.0-or-later |
| Source | GitHub repository |
| Download | Blender Extensions |
