What I think would really be nice is if someone like Peter Smid wrote a book on manually programming contours with NC Plot and included / sold a spreadsheet type of program designed to take the drudgery out of figuring out contours / managing the calculations. I'm thinking of something that showed all the possible right angle geometry situations one might encounter on prints. After you identified the correct geometry layout needed the program would then assist you by allowing you to enter information as you went along toward figuring your needed points using a systematic type of approach.
Actually, I think a project like this would be ideal for the next update to what is my favorite Peter Smid book: CNC Programming Techniques. Perhaps you and Peter Smid could do a joint project.
Here is a sample of what Peter Smid's CNC Programming Techniques book looks like:
http://tinyurl.com/29dmfo
Jon Banquer
San Diego, CA