1. Select the spline to be extruded.
2. Click Shape in the main tool palette.
3. Click Extrude in the lower tool palette.
4. Set the Extrude Options parameters as desired.
5. Click OK to create the shape, or click Cancel to abort.

Extrude Options:

Step - The number of vertices along the v-axis The minimum number is 2.
Depth - The depth (front to back) of the finished object.
Bevel - Creates a 45Á edge between both faces and the extruded object. This option will add v-steps to the finished object if needed.
Radius - How far the bevel pushes the surface out. A negative number will push the bevel inward.
Height - How far the bevel will extrude from the current face.
Front Beveling- Place a bevel on the front face of the extruded object.
Back Beveling- Place a bevel on the back face of the extruded object.