Create a 3D geometry using Runtime version 100.1

[ManelKEDDAR]

I need to create grammatically a 3D Geometry for example a 2D Cone and extrude it with a given z value but i think it doesn't exist any class or methods that permits that , like in arcObject there's IMultipatch class to represent a 3D Geometry and there's GeometryUtilities.ExtrudeAbsolute(IGEometry2D ,Z) ?

thanks

Manel