Drawing on paper has many advantages, and sometimes is simply more pleasing. I propose a ruler with a keypad and a small display on top, and the inner workings of at least three optical mice below. There is also a pin at one end, and a movable hole in a side-slider. In between is a chip integrating the information from the mice and the linear positioning of the side slider. The ruler can be used as a standard ruler, but you can also use it, then hit a button, move it around and get the angle it is now in, relative to the first position. If you lower the pin first, and insert the pen into the hole, a part-circle of defined radius and angle can be drawn. Also, circle through three points, parallels, many geometric figures etc.-- loonquawl, Apr 02 2009 Staedtler Rolling Ruler http://www.artstuff...r_rolling_ruler.htmThe analog analog version [phoenix, Apr 02 2009] I like it. I don't think you'd get a good absolute position out of optical mouse sensors, but that doesn't seem like an insurmountable problem.-- Srimech, Apr 02 2009 Thank you all for your links. Now i have two things i need to buy, and one i'll probably have to steal...-- loonquawl, Apr 02 2009 random, halfbakery