Extension Method on Factory Class

namespace Cinema {
    public interface ICinema {
    }

    public sealed class CinemaFactory {
        // Singleton pattern to support extension methods. (Can't add extension methods to static classes.)
        private static readonly Lazy<CinemaFactory> LazyInstance = new Lazy<CinemaFactory> (() => new CinemaFactory());

        public static CinemaFactory Instance {
        get {
                return LazyInstance.Value;
            }
        }

        private CinemaFactory () {
        }

        public ICinema  GetCinema (EndpointAddress10 RemoteCinemaUri) {
            ICinema CinemaEngineInstance;

            // Get a reference from the WCF service...

            return CinemaEngineInstance;
        }
    }
}

namespace Cinema.Engine {
    using Cinema;

    public class CinemaEngine : ICinema {
    }

    // Add polymorphism to the class defined in a different project.
    public static class CinemaFactoryHelper {
        public static ICinema GetCinema (this CinemaFactory _This) {
            return new CinemaEngine ();
        }
    }
}

namespace Cinema.Client1 {
    using Cinema;

    public class Consumer1 {
        // Intellisense shows that there are no overloads to the GetCinema() method. Yay!
        private ICinema ref = CinemaFactory.Instance.GetCinema (EndpointAddress10.FromEndpointAddress (new EndpointAddress ("http://localhost"));
    }
}

namespace Cinema.Client2 {
    using Cinema;
    using Cinema.Engine; // Add visibility to the extension method that provides a local instance of the engine.

    public class Consumer2 {
        // Intellisense shows the method +1 overload. Yay!
        private ICinema ref = CinemaFactory.Instance.GetCinema ();
    }
}