An accessory to convert the 3D printer (Creality Ender 3) into a cnc machine. Currently the accessory used is a Bic pen.
The pen holder consists of three parts:

• A base, connected to the fixing screws of the printer's fans. When the printer is used to print in 3d, this part does not need to be removed.
• A support for the tool (Bic pen), connected with a joint, screws and nuts.
• Pen locks.

You also need a soft spring to hold the pen on the paper sheet.

Under the sheet of paper, so as not to damage the printing surface and to have a smooth surface I put a sheet of plasticard.

To generate the g-code I used the Inkscape program, adding the instruction "G92 X0 Y0 Z0" for homing at the beginning of the g-code.
I also changed the Z coordinates (when the pen is down) from "Z-1.0000" to "Z0".
To start printing you have to place the pen at the point that will be the home (X0 Y0 Z0), with the pen touching the sheet with a slight compression of the spring.

 The conversion of the 3D printer into a plotter has also been successfully used to generate printed circuits, the circuit is designed, the gcode is created with flatCam and the copper base is colored with permanent marker. By placing a punch as a tool, the paint is removed and the work is finished by immersing the base in ferric chloride, then the paint is removed with petrol for lighters.

 At this address you will find the video:

https://www.youtube.com/watch?v=MEua65QG9g8

https://www.youtube.com/watch?v=60F_fJIbP7c

Italian version:http://www.tutorial360.it/default/tutorial.php?id=387