In my experience, curves in SketchBook Designer are extremely responsive and malleable.

(You don’t need a stylus-equipped tablet device to use SketchBook Designer, but I think you’ll get more use if you do.) This lets you create elegant curves you don’t usually expect to get with a mouse. Unlike in raster programs, the curves you draw in SketchBook Designer are editable Spline curves, so you can refine the swirls, loops, and turns by adjusting the handle points. The simple interface lets you pick your preferred brush style or pen style, then start sketching out ideas in curves. Part of Autodesk Product Design Suite 2012, SketchBook Designer 2012 is almost ready to use as is, with little or no training. That’s the market Autodesk hopes to recapture from the graphics programs that have long dominated the field with a new product: Autodesk SketchBook Designer.

But the training and practice needed to master these programs, meant for professional graphics and illustration, are not trivial. Or you might try using ACDSee’s Canvas or Corel’s CorelDRAW. You might try sketching out your ideas in Adobe Illustrator, for example. Is there a software product that lets you do what we would normally do with a cocktail napkin when inspiration strikes? There are a few, but nothing comes close to the simplicity of a cocktail napkin.

Autodesk sketchbook examples