and how he took an EagleCAD design and converted it into four GCode files. That’s one for each side of the PCB, one for through holes and one for the final outline of the PCB. These are then fed ...

Afterwards, isopropyl alcohol can be used to wash away the unexposed mask, leaving behind your PCB design. You’ll still need to chemically etch the board, and if you’re using through-hole ...