Electronic parts are a good example. Take a trip back to my schematic pages and try to envision the 3d world that they will occupy. In the photo above I'm starting to take the first steps. Once my battery boxes are installed and everything else is said and done I'm left with an L shaped space for laying out the parts. Although some of my parts are still relatively 2d and the interconnecting wire looks suspiciously like string, this still gives a good idea of how much space everything takes and how it is wired.
Wiring is a tricky subject.
This kind of electronics also benefits from keeping the wire short between the motor, contactors, and controller. What I haven't shown in the photo, nor figured out in my head yet, are which wires to run through holes in the board. Remember, the motor and one of the battery boxes will be below this board. The photo also shows rough representations of the motor, 144v battery pack, and 12v battery. The idea is to know where the wires are coming onto and leaving the board, where the high voltage sections are, and where the other control wiring and fuses are going to live.