Yesterday you peeked into a Designer's Concept Board which had beautiful hand drawn sketches.  Here is another form of sketching which is done thru the use of a computer.  The most widely used software for Designers to generate sketches thru the use of a computer, are Adobe Illustrator and Photoshop. I use these two softwares on a daily basis.  Sketches are either drawn on the computer from scratch or a library of sketches can be acquired thru trend books or sketch services. For handbags you could use Close-Up Sketchbook No.5 for Spring/Summer 2012 and available on OPR News NY. This is a great resource of what's trending in handbags with sketches readily available.