Select a shape. > Modify panel > Modifier List > Mesh Editing > Extrude
Select a shape. > Modifiers menu > Mesh Editing > Extrude
The Extrude modifier adds depth to a shape and makes it a parametric object.
Spline before extrusion, left. Extruded splines without and with Cap End selected
Interface
Amount: Sets the depth of the extrusion.
Segments: Specifies the number of segments that will be created in the extruded object.
Capping group
Cap Start: Generates a flat surface over the start of the extruded object.
Cap End: Generates a flat surface over the end of the extruded object.
Morph: Arranges cap faces in a predictable, repeatable pattern, which is necessary for creating Morph targets. Morph capping can generate long, thin faces that don't deform as well as grid capping. Use morph capping primarily if you're extruding multiple morph targets.
Grid: Arranges cap faces in a square grid trimmed at the shape boundaries. This method produces a surface of evenly sized faces that can be deformed easily by other modifiers. When you choose the Grid capping option, the grid lines are hidden edges rather than visible edges. This primarily affects any objects assigned a material with the Wire option turned on.
Output group
Patch: Produces an object that you can collapse to a patch object; see the Edit Modifier Stack section in Modifier Stack.
Mesh: Produces an object that you can collapse to a mesh object; see the Edit Modifier Stack section in Modifier Stack.
Generate Mapping Coords: Creates the extruded object with mapping coordinates already applied. When Generate Mapping Coordinates is turned on, additional mapping coordinates are applied to the end caps placing a single 1 x 1 tile on each cap.
Generate Material IDs: Assigns different material IDs to the sides and the caps of the extruded object. Specifically, the sides receive ID 3, and the caps receive IDs 1 and 2.
Use Shape IDs: Uses the material ID values assigned to segments in the spline you lathed.
Smooth: Applies smoothing to the extruded shape.