The motor housing on the blow-dryer model is a surface of revolution. The source curve for the housing was created from a top view and then rotated 90
around the X axis to orient the curve for the revolve construction. A line was drawn from the center of the housing down in Z to act as the axis for the revolution. Later, this model uses a cap surface to complete the housing as an example of the cap surface.
Set the surface for a full 360 of revolution. Select the axis and the curve to pass around the axis and the result is shown in the second image. You could also have created this same surface as a sweep around the circle.
If the source curve had extended all the way to the rotation axis, the housing could be completed in one step. A drawback to this method is that the central boundary would be degenerate (a point) and may not provide good machining results.