A method sometimes used on PCB's that must carry large currents into themselves and out again.
A piece of 16 or 14 gauge tinned bare copper is bent and laid down over top of and soldered to the copper trace, or even better, the design brings the large current wires directly to the places where they enter and leave the board.
Running such large currents through a pcb without 'cheating' is hard to do without it having a large effect on the nearby circuits.
Basically, such things are not done in the production of electronics products. They are avoided with techniques, tricks, or whatever you want to call it. You should devise a way of bringing the current to where it needs to be without running it through the PCB like all the other twisted, maze-work like, traces you are so used to seeing.