The Design Process

I do not know how many posts this is going to be or if this is going to be a consecutive series or random bunch of posts.  I am starting to do my own line of toys.  It is not that I have completed all that I want to do in my books or cannot find anything on the internet.  There is just a sense of great accomplishment I feel when the design is all mine.  Designing is something that I have always enjoyed.  This is probably a reason I am in the R&D department at work.  I am hoping to convey some of the ideas and patterns that I use when I am working on a design project.
One of the first rules in the beginning stages of design is that everything is possible.  It is far too easy to think of an idea and dismiss it without a second thought because there is some flaw in it.  I want to create toy plans that uses standard dimensioned lumber (thickness) and people can make with basic power tools (table saw,drill press, table router, and either a band saw or scroll saw).  This is my first design in this endeavor:

One huge problem, I do not have a lathe.  I cannot make the broiler on the engine.  Not a problem, the broiler is a purchased leg that I found at Lowe's.  The entire design of the engine is based around that piece.  Another thing that could have worked is a rolling pin. This was actually my first idea.
A great place to get ideas is look around, never limit the idea at this stage.  Magazines and window shopping are great ways to get ideas.  Think of ways to do things better.  The concept of the train came from a toy circus train.  Different parts of train come from different trains that I have made in the past.  For example, the caboose has elements general train, the box car is similar to the puzzle train.  Each of them have my own twist to them.  The top decoration is my design along with the decoration by the wheels.  The cage car is something I did.  I want the exposed dowel look to be more of my signature look.  The picture comes from a rendering done in a 3D modeling system.  That is going to be detailed in another post.
Another thing to remember is not to toss out an idea because there is "no possible way" it can be made, parts do not exist, there is no way it can be assembled, etc.  At this stage anything can happen.  Designs may have to change or be redesigned to over come these obstacles, but that is not in this stage of design.
Another good thing to have around is a sketch book.  This may be a simple spiral bound with blank sheets in it or just plan printer paper.  I like the spiral bound because I can keep the drawings some what organized and I don't loose them.  The sketch book is to put the ideas on paper.  This is by no means a final design.  It is a way to get the ideas out of the mind and on a tangible document.  This is where a lot of the problems come out and are solved.  Add notes and concerns to the sketches.  This is not the place to solve all problems.  For instance, I really did not know how I was going to put the bars in the cage car and caboose.  The sketch did not solve the problem, it was something that I have to figure out on my own.  I have a plan, but not sure it is going to work out.  The down side of this necessary step is that it does not put parts into perspective.  At this point I get excited about the project and  want to get right into it.  Unfortunately this would be a mistake.  Proportions are important in a project. 
I will end on this side note.  I was listening to a podcast where they made the statement that they really do not measure their parts.  They determine the critical dimensions and base everything else off of these dimensions.  I heard that and thought it was absurd. Come to realize they are more right than I thought. For example, my last truck.  My key dimension was the length and width of the chassis. The cab was a little long and I planed the wood down a little too much for the bucket.  This was never a show stopper because I knew how the other parts related to each other.  Some parts had to grow and some had to shrink.  It is the relationship of the parts that is important.