Fine Line Prototyping comes from two things. The first is creativity while the other is innovation.
The first part, which is often the most difficult, is finding a need in order to make that product. The second is putting those ideas together and conducting research and development until this can be made commercially for public use.
If the company has been in the industry for a long time, the marketing department can conduct research studies to find out what are the needs of the market. An inventor does not have these resources so the best reference will be friends and strangers on the streets that could give insight into the problem.
When the information has been collected, the designer will then come up with the end solution just like putting an X mark on a map. The challenging part, which will take up a lot of time, will be how to get to that spot.
Large companies can set a budget to get started while the inventor who is not well funded can write a proposal requesting for a grant. Out of a thousand ideas, perhaps only five will get to the next stage so that the group will be more focused on the task at hand.
There will be a lot of trial and error with each experience making the person come closer to a model. Various designs will also be made so this can be tested and should it breakdown, another unit will be sent in to continue with the work.
Airplanes use wind tunnels before allowing a prototype to be flown by a test pilot. Automobiles drive through various road and weather conditions. When the product has passed all the tests, this is the time the model can begin initial production.
The marketing department will pre-launch the model into the market and then have a grand opening where it will be finally introduced.
The biggest test is how customers will react to the product. A rival company may have something better, there may be a problem with the pricing and other things that have to be analyzed again so this can be corrected.
The cycle of fine line prototyping is done in making other products and is the same in almost any industry. The system may not be perfect but with the help of technology and the feedback of the customers, this practice will continue as it has for more than a hundred years.