Lee Schierer McKean, PA
What I do is to look at how others have made items and use enhancements or details that they have used to incorporate into my designs. I know what size the final piece needs to be and I design the piece to fit that space. I can draw several iterations on cad to see what the finished piece will look like and make changes if needed. I do most of my design work in AutoCad to get exact dimensions for components. Typically to save time I don't draw all the details of the joints and just make the required adjustments to pieces as they are made.

Lee