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.

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