The cad/pcb port
pcb-4.1.3p0v0 – printed circuit board layout tool
PCB is an interactive printed circuit board editor for the X11 window
system. PCB includes a rats nest feature, design rule checking, and can
provide industry standard RS-274-X (Gerber), NC drill, and centroid data
(X-Y data) output for use in the board fabrication and assembly process.
PCB offers high end features such as an autorouter and trace optimizer
which can tremendously reduce layout time.