3D Extrude is intelligent object generated when a face or contour (polyline) is assigned a height.

3D extrude object has next properties:

• Extrusion height: The extruded object's thickness
• Create handles: This option creates a handle at each vertex
• Material: Opens the drop-down menu for materials
• Edges: Defines the visibility of vertical edges
• Filleting Radius: Filleting of top or bottom face

An extruded object has extended form called freeform which consists of multiple contours on top of each other defined distance between them.
Free forms can be used to model many different shapes by editing each of contours and changing distance between them.