One of the best parts of being a rodmaker is testing out new rod models. The process can be a lengthy one. Sometimes you're inspired by another model that you come across, sometimes you're just in the a mood to do something new and you start with a less defined direction.
For me, the process that I follow most is designing to solve a particular problem. Usually this is prompted by a fishing experience of my own or occasionally by a customer or friend. "You know", they'll say, "I was fishing at so-and-so a place and there were a lot of branches overhanging the stream. Small water, small fish, lots of hiking, and it was really tough too...". That's the kind of thing that usually gets a rodmaker thinking.
Most of the time I don't talk about a new rod until I have spent some time testing it. I fished my 6'9" salmon rod for 3 years and landed about 20 salmon before I showed it to anyone. Lawn casting is well and good, but I really don't think that a few minutes doing that really tells you much. Especially if you are trying to develop a rod for actual fishing conditions. I even heard a story about a rodmaker who delivered a new design to a customer who broke it on the first cast. Yikes.
All of this is top-of-mind since I put together a new 6' #4 design last summer and finished the prototype in time to take on a trip to the Poconos. My intended design was a short rod that could push out a big fly accurately to at least medium distance (the previous year I had caught some large fish there in small water on large craneflies). The model sure felt good in lawn casts, but it really needed to be tested on the river. Here are a few of the trout that helped me do exactly that. Nice work if you can get it.