SketchUp extension · free

Smart Spline

Smooth, organic 3D curves with zero configuration. Point, click, and the curve finds its path through your geometry.

Why Smart Spline

SketchUp’s standard tools struggle with organic shapes, and the plugins that handle them bury you in dialog boxes before you draw a single line.

Smart Spline does the opposite: no window, no setting. You draw directly in the 3D view, like a native tool.

No interface
No pop-up hiding your model. You draw in the viewport.
Live preview
An orange guide shows how the curve will behave before you click.
Automatic smoothing
The curvature is recalculated from your last four points, and the number of segments follows it.
Truly 3D
Points snap to vertices, edges and faces: handrails, terrain contours, cables, organic furniture.

Place the points
Left-click to place a control point. The curve passes through every point you click (Catmull-Rom), with no tangent handles to adjust. SketchUp’s inferences still work: snap to vertices, edges or faces.
Finish
Double-click on the last point, or press Enter, to finish an open curve. Click on the first point to close the loop.
Correct as you go
Backspace removes the last point, as many times as needed. Don’t use Ctrl+Z while drawing: it cancels the whole curve.