So what if you want to ditch the pencil and paper and move to a more precise form of drawing up your plans but don't want to spend a bunch of money just to draw them up? Simple, download this free CAD program and get to drawing. Sure, its a little limited, but should work well for most people.
Google SketchUp
Lots of designers using Google's SketchUp program to design parkjets now too. They have a limited free version and a paid version as well.