private void CreateRectangle(Curve2d C1, List <Curve2d> Cs)
        {
            var C2 = Cs.First();

            var sp1 = C1.StartPoint;
            var ep1 = C1.EndPoint;
            var Ps1 = new List <Point2d> {
                sp1, ep1
            };

            var sp2 = C2.StartPoint;
            var ep2 = C2.EndPoint;
            var Ps2 = new List <Point2d> {
                sp2, ep2
            };

            var Ps = from p1 in Ps1
                     from p2 in Ps2
                     let d = p1.GetDistanceTo(p2)
                             orderby d descending
                             select new List <Point2d> {
                p1, p2
            };

            if (Ps.Any())
            {
                var Points = Ps.First();

                var Vec1 = CADUtil.GetVector(C1);
                var Vec2 = CADUtil.GetVector(Points[0], Points[1]);

                if (Vec1.GetAngleTo(Vec2) > Math.PI / 2)
                {
                    Vec1 = -Vec1;
                }

                double Ang = Math.Abs(Vec1.GetAngleTo(Vec2));

                var P1 = CADUtil.ToPoint3D(Points[0]);
                var P2 = CADUtil.ToPoint3D(Points[1]);

                CADUtil.CreateRectangle(P1, P2, Vec1, Ang);
            }
        }