CAD Curve documentation

CAD-style drawing tools inside Blender. Click to draw, type a length if you want an exact size, and confirm. Previews stay temporary until you finish, so Cancel never leaves leftover geometry.

Version 1.0.1 · Blender 4.2+ · Windows, Linux, macOS
Website / support: https://linktr.ee/mashud008

Features

• Arch, rectangle, circle, ellipse, polyline, and NURBS spline drawing

• 2D Offset, Fillet, and Chamfer on planar curves and meshes

• SketchUp-style Guide Tape with snappable dotted construction lines

• Live dimensions and typed measurements (2m, 5, width,height)

• Scene units: metric, imperial, or unitless

• Ortho lock, grid snap, and vertex / midpoint / edge / face snap

• Working planes, including Auto Surface and Surface Curvature

• Tools on the T-toolbar, Add → CAD Curve, and the N-panel

No extra Python packages are required.

Install

CAD Curve is a Blender 4.2+ extension.

1. Open Blender 4.2 or later (tested on 4.2 LTS, 4.5 LTS, and 5.2 LTS).

2. Go to Edit → Preferences → Extensions.

3. Open the dropdown and choose Install from Disk…

4. Select the CAD Curve ZIP and enable CAD Curve.

5. Restart Blender after an update so older modules are not cached.

6. In a 3D View, press T. The tools sit at the bottom of the toolbar.

If your Blender build still shows Edit → Preferences → Add-ons → Install…, that also accepts this ZIP.

The same tools are under Add → CAD Curve and the N-panel tab CAD Curve.

Quick start

1. Move the mouse into a 3D View.

2. Choose a CAD Curve tool from the T-toolbar.

3. Click to place points. Move the mouse to preview dimensions.

4. Type a length for an exact size (2m, 5, or width,height), then Enter.

5. Enter or the last click confirms. Esc or right-click cancels and creates nothing.

Object Mode creates an editable curve. Mesh Edit Mode appends the result into the active mesh.

After a tool finishes, press F9 for Adjust Last Operation (plane, snaps, measurements, and transform). Use Blender undo after geometry exists.

Drawing tools

Arch

• 3 Point Arch — start, end, then a point on the arc. Type a chord length, then S for sagitta or R for radius.

• Center Point Arch — center, start, end.

Rectangle

• Center Rectangle — click the center, then a corner. Type width,height (one number makes a square).

• Start/End Rectangle — opposite corners.

• Rounded Rectangle — opposite corners; press R and type a corner radius.

Circle

• Center Point Circle — click center, then size. R is radius mode, D is diameter mode.

• 3 Point Circle — three points on the circle.

• Ellipse — click center, then a corner. Type width and height.

Curve

• Polyline — click corners continuously. C closes the shape. Alt+F fills a closed outline as an n-gon face. Backspace undoes the last point when the number field is empty. Enter or right-click finishes.

• Spline — smooth NURBS spline with the same Backspace undo. Enter or right-click finishes.

Modify tools (2D only)

Offset, Fillet, and Chamfer work on planar curves and meshes. 3D solids are rejected.

Offset

AutoCAD-style parallel copy.

1. Choose Offset.

2. Click a 2D line, polyline, spline, rectangle, arc, circle, or planar mesh.

3. Move the mouse to the side you want.

4. Type a distance such as 0.2 or 2m, then Enter — or click to confirm.

Circles and arcs stay concentric. Polylines and rectangles get mitered corners. Splines stay smooth. A planar mesh face becomes a new mesh copy. Backspace lets you pick another source.

Fillet

Round one corner, or every corner, of a 2D curve or mesh.

1. Choose Fillet.

2. Click the line or corner you want on a planar polyline, rectangle, or mesh.

3. Only that corner is changed. Press A if you want every corner.

4. Type a Radius (0.2, 50mm) or move the mouse, then Enter or click.

The source object is edited in place.

Chamfer

Cut one corner, or every corner, of a 2D curve or mesh.

1. Choose Chamfer.

2. Click the line or corner you want on a planar polyline, rectangle, or mesh.

3. Only that corner is changed. Press A if you want every corner.

4. Type Distance 1 and Distance 2 (Tab or comma switches fields). One value uses the same distance on both edges.

5. Enter or click to confirm.

The source object is edited in place.

Guide (Tape)

SketchUp-style dotted construction lines. No measurement labels are drawn on the guide.

Offset from an edge

1. Choose Guide (Tape).

2. Click a mesh edge (for example the bottom of a 3 m cube).

3. Move the mouse along the offset direction.

4. Type 2m and press Enter (or click). A dotted guide sits 2 m from that edge.

Free guide — if the first click is not on an edge, the tool draws a guide between two points and asks for Length.

Guides go into the Guide_Tape collection. They do not render.

Length (Preferences or N-panel):

• Full World — spans the world; World Size is the total length (default 1000).

• Fixed Length — uses the Length value.

• Match Source — matches the source edge or measurement.

Style:

• Real Dashes — real short edges, so Blender’s magnet snap can hit the guide.

• Overlay Dots — zoom-scaled overlay; CAD Curve tools still snap to it.

Always Snap To Guides (on by default) snaps to guides without holding Ctrl/Cmd.

You can snap to endpoints, the midpoint, anywhere along the line, and intersections of two guides. For Blender’s native tools, enable magnet snap with Vertex and Edge.

N-panel → CAD Curve → Guide Layers lists every guide. Hide, delete one, or delete all.

Snapping the first drawing point to a guide also moves the drawing plane to that height, so a shape started on a 2 m guide stays at 2 m.

Shortcuts

Drawing plane

Press P to cycle: Auto Surface, View, Surface, Surface Curvature, XY, XZ, YZ.

Auto Surface (default) uses the face under the cursor. Flat faces pick XY, XZ, or YZ; angled faces use the face tangent. If nothing is hit, a view-aligned axis plane is used.

Surface Curvature drapes the curve on the mesh instead of staying on a flat plane. Sphere and cylinder draws stay on the surface. Surface Samples (F9) controls how densely segments are draped. Plane Offset lifts the curve along the surface normal.

The plane locks after the first point so a circle or rectangle stays planar.

Snapping

• Grid — viewport subdivisions when Grid Size is 0, or the Grid Size you set.

• Vertex / Midpoint / Edge / Face — visible mesh and earlier CAD Curve geometry.

• Hold Ctrl/Cmd for grid snap. G, V, M, E, F toggle modes without the modifier.

• A circular marker follows the active snap. Guide snaps use a light-blue marker.

• Circle and ellipse stay free even if Blender’s global magnet is on.

Units and measurements

Dimension text and typed values follow Scene Properties → Units. In millimeters, 5 is 5 mm. In meters, 5 is 5 m. You can also type a unit suffix such as 2m.

Up/Down browses recent values. N-panel → Recent Measurements can clear that history.

Preferences

Edit → Preferences → Add-ons → CAD Curve, or the 3D View N-panel CAD Curve tab:

• Curve Vertices is a slider, not a toolbar tool. Open the N-panel (press N), choose the CAD Curve tab, and change Count. The same slider appears in the top bar while a CAD Curve tool is active. Circles, ellipses, arcs, fillets, and rounded corners use this count. Press [ or ] while drawing to change it.

• Guide style, dash size, length mode, world size, always-snap

License

GPL-3.0-or-later. Copyright 2026 RANA3D.

Support

RANA3D — https://linktr.ee/mashud008