To fast prototype interconnection PCBs using direct ink on copper, I made a simple pen plotter using some old printers part. The y axis is a carriage of a dot matrix printer, the z axis is a part of a small impact printer, the x axis is simple a wood table moving on two shalf. Despite the coarse appearance, the small plotter gave very good results as can be seen from the video.

( https://youtu.be/mzp-oJISSq8 )

The motors driver circuit consist in two drv8825 board for the x/y axis and a unl2803 for the z axis.

The controller board is based on a STM32F103 bluepill board, a small TFT module, a keypad and a spi flash memory to store the plot files.

The board firmware include a small file system and the plot routine to drive the motor.

I also developed two small PC utility to perform:

1. Parser the Gerber file produced by Eagle Cad to remove pad holes, to traslate smd pad to lines, to doubled the lines with thikness greather than phisical pen and so on.
2. Store the obtained vector file in the controller flash memory file system using the ST     USB-VirtualCOMPort for the next stand-alone run    

Both Firmware and PC utility are in development (beta stage). When I'll obtain a stable version I'll release the project as open source.