About an Extruded Surface
With the Extrude tool, you can create an extruded surface by extruding a sketched section to a specified depth in the direction normal to the sketching plane.
• Define the depth of the extruded surface using one of these depth options:
◦ 
Variable—Extrudes a section from the sketching plane by the specified depth value.
Variable—Extrudes a section from the sketching plane by the specified depth value.◦ 
Symmetric—Extrudes a section on both sides of the sketching plane by half of the specified depth value.
Symmetric—Extrudes a section on both sides of the sketching plane by half of the specified depth value.◦ 
To Reference—Extrudes a section to one of the following:
To Reference—Extrudes a section to one of the following:▪ 
—Extrudes to a selected point, curve, plane, surface, quilt, or body.
—Extrudes to a selected point, curve, plane, surface, quilt, or body.▪ 
—Extrudes to an offset of a selected point, curve, plane, surface, quilt, or body.
—Extrudes to an offset of a selected point, curve, plane, surface, quilt, or body.▪ 
—Extrudes to a translation of a selected point, curve, plane, surface, quilt, or body.
—Extrudes to a translation of a selected point, curve, plane, surface, quilt, or body.• An extruded surface can have open or closed ends. To create a closed volume from the extruded surface, select 
Capped Ends to create additional surfaces that close the ends of the feature.
Capped Ends to create additional surfaces that close the ends of the feature. | The Capped Ends option requires a closed section. |