How about a different spin? While the factory method was certainly fast, and the particular process did not require a high level of skill, consider what it would take to replicate it exactly. A moving assembly line, a "bath" of primer, spray nozzles with pumping and pipes/hoses to connect the dots.
So when we talk spray cans, syringe needles, and other alternatives, I think it is more of combining inginuity and frugalness. I think the alternatives are less complicated in comparison to the original method.