Pen holder for EV3 Drawing robot

This set includes a pen holder for the [EV3 Print3rbot](http://www.ev3dev.org/projects/2014/07/16/Drawing-Robot/) and a 40 tooth gear not included in the EV3 Home Edition set. The __beam_pen2.stl__ must be printed twice. [Project page with building instructions and Python code for ev3dev](www.ev3dev.org/projects/2014/07/16/Drawing-Robot/) The file beam_pen.stl has been resized to allow a better fit of beam_pen2.stl. https://www.youtube.com/watch?v=9pjpQoZoW6E https://www.youtube.com/watch?v=UwpghsdmDsE