Use the Tube Surface tool to create a variable radius tube surface that uses free curves as a path.

1. Choose Surfaces > Tube Surface.
2. Select a curve

   The curve is highlighted in yellow and a blue radius manipulator appears at the start of the curve.

   Note

   If the Chain Select option is turned on, curves that are tangent continuous with the selected curve will also be selected.

3. Adjust the radius by dragging the mouse on the blue circle, or by entering a value on the prompt line.
4. Click along the curve to create extra radius manipulators, if necessary.
5. Do any of the following:
   • Change the position of a manipulator by clicking and dragging the small circle at the center.
   • Change the radius of a manipulator by clicking and dragging on the larger circle.
6. Click the Recalc button.

   A tube surface is produced.

   You can keep modifying or adding radius manipulators then press Recalc again to modify the tube surface.

This tool maintains construction history. Modifying the curve will update the tube surface. Selecting the surface then choosing the tool again lets you modify the radius manipulators some more.