Mr. Drew is running very well thanks to a demanding specification from Judith Cottrell. Also Sandy Noble and his brilliant “polargraph” concept and software expertise. Of course there is Open Hardware such as Arduino and Adafruit Motor Shield. Also there is Processing.org open source software.
The machine can use markers or pens and has pen angle adjustment. It has a pinch handle that allows easy pen switching. It can scribble on paper or glass (since the pen tilt permits pens with large ink tanks. Also the contact point of the pen with the drawing surface is visible so you can see the action in real time.
A second machine is on it’s way to Artpace (with more improvements). It will use a more versatile spool mounting system and NEMA 10 stepper motors.