You don't have to use a ResX to embed some static data in an assembly.

With Visual Studio, you can just add the file (Add a New Item or Add an Existing Item), change the Build Action (F4 or Properties Window) to "Embedded Resource", and you can then load it with a piece of code like this (NOTE: should be in the same assembly to avoid security issues):

using (Stream stream = Assembly.GetExecutingAssembly().GetManifestResourceStream("ConsoleApplication1.MyFile.MyExt"))
{
   // load data from stream
}

I suppose here the file is MyFile.MyExt, and this file is directly added to the project root, as VS automatically adds the current project namespace - here ConsoleApplication1 - to embedded resources path.

If you are unsure about this path, I suggest you use a tool such as .NET reflector that is capable of displaying embedded resources names and data from an assembly.

This will get you a Stream instance. So you can store any kind of data provided you can load/save it from/to a Stream instance (MemoryStream, StreamReader, DataSets, .NET or Xml serialized objects, Bitmaps, etc.)