Rui written an article on how to build your own PCBs using a CNC machine. Rui Cabral writes:
The PCB manufacturing method i used before buying my CNC machine was the lithography method and worked as follows:
First i printed the board design on an acetate sheet.
This sheet was placed over a pcb with a light sensitive coat and placed under UV light for several minutes.
The pcb was then immersed in a solution of caustic soda to remove the photo sensitive material that was “damaged” with the UV light.
The pcb was then immersed in a Ferric Chloride solution to remove the copper.
After the copper being removed i then washed the pcb to remove the chemicals and then i needed to cut the plate and finally drill the pads.
Making PCBs with CNC – [Link]