Once a circuit has been designed it needs to be converted to a
Printed Circuit Board (PCB) design so that it can be manufactured.
When I first started my career this process was done entirely by hand.
First you worked for days or even weeks with pencil and paper on a huge
sheet of graph paper until you had all the tracks routed correctly. Then
you went to using self-adhesive tapes on sheets of mylar, working on a
light box at a scale of 2:1, to create the camera-ready artwork.