rotateextrude

rotate extrude, often written as rotate_extrude in OpenSCAD, is a 3D modeling operation that creates a solid by rotating a two-dimensional profile around an axis, typically the Z axis. It is used to generate objects with rotational symmetry, known as solids of revolution.

In OpenSCAD, rotate_extrude(angle = 360, $fn) sweeps a 2D shape around the Z axis to form a 3D object. The default angle is 360 degrees, producing a complete solid. Supplying a smaller angle yields a partial revolution, producing sector-like or partial objects. The 2D profile to be rotated is defined in the XY plane, and the axis of rotation is the Z axis.

A common way to illustrate its use is to create a torus by offsetting a profile from the origin. For example: rotate_extrude(angle = 360) translate([20, 0]) circle(r = 2); This translates a small circle 20 units from the origin and spins it around the Z axis to form a torus with major radius 20 and tube radius 2. Other profiles, such as polygons or paths that widen or narrow, can produce vase-like or bowl-like shapes when rotated.

Parameters include angle, which controls the extent of rotation, and $fn, which controls the resolution of the resulting surface. There is no center parameter in rotate_extrude; the relative position of the profile to the rotation axis determines the final shape.

See also: solids of revolution, OpenSCAD.