Two days of machining and a whole lot of thinking and I have finished making a tool for my lathe. It is a radius cutter to cut concave and convex curves on the lathe.
The first thing that was made with it was the last part to finish it. A brass sphere for the handle. See the video to see how the tool is used.
http://www.flickr.com/photos/lostmachine/4161794673/