This Stack Overflow question ("explaining software development to management") had a really brilliant comment on one of the answers.
Analogies are always leaky, and you will end up with proposed solutions that solve the analogy, not your actual problem. Just explain the problem in simple terms without comparing it to anything physical. Read Edsger Dijkstra's famous 1036 and 854 for an insight into the horrors thinkign by analogy is inflicting upon us
EWD 854, "The fruits of misunderstanding". "when faced with something new and unfamiliar we try to relate it to what we are familiar with". "a program is an abstract mechanism". "the mechanism being abstract, its production is subsumed in its design. In this respect a program is like a poem: you cannot write a poem without writing it. Yet people talk about programming as if it were a production process and measure 'programmer productivity' in terms of 'number of lines of code produced'."
Aha. Software production is subsumed in its design. There is no "production" other than design. We design at a high level. We design code. When we've designed the code, we're done. There is no further development effort.
EWD 1036, "On the cruelty of really teaching computing science". "From a bit to a few hundred megabytes, from a microsecond to a half an hour of computing confronts us with completely baffling ratio of 109"
Love that cautionary note. Computer science forces us to confront layers of meaning that have a huge scope.
I'll have to work my way through the archive. It will probably take years to read through all the manuscripts.
Wait -- I've Got One Of Those
Back in the 70's, the undergrads at Syracuse University were given copies of EDW316. At the time, it was just a paper on the art of programming. It sat in a file drawer for decades. I unearthed it recently.
At the time, EDW316 looked like a course number. I assumed -- wrongly -- that it was notes from some other school of computer science. Turns out, it was one of those EDW missives. It had found it's way into the hands of the CS Faculty at SU. From there, a copy fell into my hands. Not until recently (30+ years later) did I realize exactly what it was a copy of.