Rapid Prototyping is a fairly new process for making short runs of plastic parts from exact 3D drawings. Orthographic views [drawings that machinists are used to] can be made faster, by viewing a 3D model from several directions, than by manually drawing in 2D, view by view.
First class 3D drawing packages like AutoCad, SolidWorks, and Pro-E, are outlandishly expensive. They RENT for thousands and thousands a year. An exception is TurboCad. I bought TurboCad 12 Pro, complete with printed manual, for a little over $100. Learning to draw was easier than I expected. I have now drawn orthographic views, from which a machinist has made parts, a couple of dozen times. The Figures for my last three provisional applications were "hidden line" views in Turbocad's "Paper Space" of a 3D assembly in "Model Space".
I encourage other inventors to follow my lead. Search third party software sites for an older version of TurboCad Pro. Don't bother with TurboCad Deluxe. It's worthless! Just start drawing in 2D. Refer to the printed manual. The tutorial is not much help. Relax! Have fun! View it as you would an interesting puzzle!