I made this a while ago to help a bit with mapping. This is basically the outline of the map which you get when you press "m" in-game. According to all the research which I've gathered, the map is 512x512 so the outline is 512x512 pixels wide. With some simple mathematics each square is determined to be 64x64 pixels. Each line is 2 pixels wide and I'm not sure whether this is 100% accurate with a regular map. I've also highlighted the exact centre of the map which is 4 highlighted pixels around the exact centre 256,256. It's easily editable in Paint and is currently saved in .png format. I can see that you may be able to use this to create an outline of your map to then build in the actual game.
Anyways enjoy and do whatever you'd like to do with it :D