public void Create3dPoly() { Point3d[] pt = new Point3d[4]; pt[0] = new Point3d(0, 0, 0); pt[1] = new Point3d(10, 0, 50); pt[2] = new Point3d(30, 20, 60); pt[3] = new Point3d(-30, 50, 70); Point3dCollection pts = new Point3dCollection(pt); ObjectId poly3dId = ModelSpace.Add3dPoly(pts); }