Reference:Cone

The cone statement creates a finite length cone or a frustum (a cone with the point cut off). The syntax is:

CONE:
  cone {
    <Base_Point>, Base_Radius, <Cap_Point>, Cap_Radius
    [ open ][OBJECT_MODIFIERS...]
    }

The geometry of a cone.

Where <Base_Point> and < Cap_Point> are vectors defining the x, y, z coordinates of the center of the cone's base and cap and Base_Radius and Cap_Radius are float values for the corresponding radii.

Normally the ends of a cone are closed by flat discs that are parallel to each other and perpendicular to the length of the cone. Adding the optional keyword open after Cap_Radius will remove the end caps and results in a tapered hollow tube like a megaphone or funnel.