A part or parts can be extruded to the next higher ordered part using the Extrusion feature. Namely, a 1d line can become a plane, a 2D surface can become a volume, etc. This extrusion can occur in a rotational way (making the whole pie from a thin slice) such as would be needed for reconstruction of a model from an axi-symmetric slice. Or it can be done in a translational manner - as if the part were glued in place, but could be stretched in one direction.

For rotation extrusions, you must define an origin and axis vector in the global coordinate system, about which the rotational extrusion will occur, as well as the number of slices and the total rotation angle to sweep through. For translation extrusions, you define a direction vector in the global coordinate system, as well as the number of slices and the total distance to stretch.