Simple helper methods for spawning/closing an attached console to a Windows application.

ConsoleHelper.cs

using System;
using System.Runtime.InteropServices;

namespace MyNamespace
{
	public static class ConsoleHelper
	{
		private const int SW_SHOW = 5;

		public static void Show()
		{
			var handle = GetConsoleWindow();
			if (handle != IntPtr.Zero)
				ShowWindow(handle, SW_SHOW);
			else
				AllocConsole();
		}

		public static void Close() => FreeConsole();

		[DllImport("kernel32")]
		private static extern bool AllocConsole();

		[DllImport("kernel32")]
		private static extern bool FreeConsole();

		[DllImport("kernel32")]
		private static extern IntPtr GetConsoleWindow();

		[DllImport("user32")]
		private static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
	}
}