Your world is a completely flat surface in which you can move forward, backward, left, right, or any combination or fraction of these. Yet there isn't such a thing as up or down. In any project like this there comes a time to go from the two dimensional world of paper drawings and suppositions to the 3d world of squeezing things into non-imaginary spaces.
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.