Как на C# коздать Си-подобную DLL(которую можно динамически подгружать)?

extern "C" __declspec(dllexport) int Run() {
	return 488;
}

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace wfa
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            MyClass.LoadDll(@"D:\dev\csharp\test\Debug\cpx.dll");
            var result = MyClass.Run().ToString();
            MessageBox.Show(result, result);
        }
    }

    public class FunctionLoader
    {
        [DllImport("Kernel32.dll")]
        private static extern IntPtr LoadLibrary(string path);

        [DllImport("Kernel32.dll")]
        private static extern IntPtr GetProcAddress(IntPtr hModule, string procName);

        public static Delegate LoadFunction<T>(string dllPath, string functionName)
        {
            var hModule = LoadLibrary(dllPath);
            var functionAddress = GetProcAddress(hModule, functionName);
            return Marshal.GetDelegateForFunctionPointer(functionAddress, typeof(T));
        }
    }

    public class MyClass
    {
        public delegate int FnDelegate();
        public static FnDelegate Run;

        public static void LoadDll(string path)
        {
            Run = (FnDelegate)FunctionLoader.LoadFunction<FnDelegate>(path, "Run");
        }
    }
}