利用AutoCAD 2004 类型库创建菜单，AutoCAD菜单是加载的acad.mns。
AutoCADConnector.cs

using System;

using AutoCAD;

using System.Runtime.InteropServices;

namespace AddMenu

{

    public class AutoCADConnector : IDisposable

    {

        private AcadApplication _application;

        private bool _initialized;

        private bool _disposed;

        public AutoCADConnector()

        {

            try

            {

                // Upon creation, attempt to retrieve running instance

                _application = (AcadApplication)Marshal.GetActiveObject("AutoCAD.Application.16");

            }

            catch

            {

                try

                {

                    // Create an instance and set flag to indicate this

                    _application = new AcadApplicationClass();

                    _initialized = true;

                }

                catch

                {

                    Console.Write("请安装AutoCAD");

                    throw;

                }

            }

        }

        // If the user doesn't call Dispose, the

        // garbage collector will upon destruction

        ~AutoCADConnector()

        {

            Dispose(false);

        }

        public AcadApplication Application

        {

            get

            {

                // Return our internal instance of AutoCAD

                return _application;

            }

        }

        // This is the user-callable version of Dispose.

        // It calls our internal version and removes the

        // object from the garbage collector's queue.

        public void Dispose()

        {

            Dispose(true);

            GC.SuppressFinalize(this);

        }

        // This version of Dispose gets called by our

        // destructor.

        protected virtual void Dispose(bool disposing)

        {

            // If we created our AutoCAD instance, call its

            // Quit method to avoid leaking memory.

            if (!this._disposed && _initialized)

                _application.Quit();

            _disposed = true;

        }

    }

}

 //程序代码。

using System;

using System.Collections.Generic;

using System.Text;

using AutoCAD;

namespace AddMenu

{

    class Program

    {

        static void Main(string[] args)

        {

            using (AutoCADConnector connector = new AutoCADConnector())

            {

                AcadApplication acadApp = connector.Application;

                AcadMenuGroup mnugrpRAA;

                mnugrpRAA = acadApp.MenuGroups.Item(0);

                // Menu

                AcadPopupMenu mnupop;

                try

                {

                    mnupop = mnugrpRAA.Menus.Item("文件(&F)");

                }

                catch

                {

                    mnupop = mnugrpRAA.Menus.Add("文件(&F)");

                }

                string strCmd;

                AcadPopupMenuItem mnupopItem;

                strCmd = "start SaveToServer;";// 这个就是你要执行的外部程序.

                mnupopItem = mnupop.AddMenuItem(7, "保存到服务器", strCmd);

                mnupopItem.TagString = "ID_SavetoServer";

                mnugrpRAA.Save(AcMenuFileType.acMenuFileSource);

            }

        }

    }

}