Pen Holder Attachment for CNC Plotter

This is my design for a pen holder attachment for my DIY CNC machine (based on the Openbuilds Acro). Inspiration for this design came from the [Parametric pen holder for CNC](https://www.thingiverse.com/thing:1287138) by yannpom. Design considerations included using screws and heat set inserts for holding the pen tightly. I also designed the holder to be printed with the arm flat on the print bed, to allow for easier printing.

The pen holder attachment is mounted to a mini linear rail z-axis using a mounting plate that I also custom designed. I have included Fusion 360 and STEP files so that the design can be modified for the mounting plate on your CNC.

Here is a [video of the pen plotter in action](https://www.youtube.com/watch?v=h9Tk5VGLiG8), drawing Serenity (from Firefly).