Extrude Polygons Along Spline Dialog

Pick Spline—Click this button and then select a spline along which to extrude in the viewport. The spline object's name then appears on the button.

If you open this dialog after performing a manual Extrude Along Spline, the name of the spline you used appears on the button.

Align to face normal—Aligns the extrusion with the face normal, which, in most cases, makes it perpendicular to the extruded polygon(s). When turned off (the default), the extrusion is oriented the same as the spline.

Rotation—Sets the rotation of the extrusion. Available only when Align To Face Normal is turned on. Default=0. Range=-360 to 360.

Segments—Specifies the number of polygons into which each extruded side is subdivided. This setting also applies to manually extruded polygons.

Taper Amount—Sets the extent to which the extrusion becomes smaller or larger along its length. Negative settings taper the extrusion smaller; positive settings taper it larger.

Taper Curve—Sets the rate at which the tapering proceeds. Lower settings result in a more gradual taper; large settings result in a more abrupt taper.

Taper Curve affects the thickness of the extrusion between its endpoints, but not the size of the ends.

Twist—Applies a twist along the length of the extrusion.

When using this option, increasing the number of segments will improve the smoothness of the extrusion.