kitemaster: 'cad packages' is a broad term, industry guys would generally call something like rhino a nurbs modelling package. it using relational data to define the shapes of all objects in a system. so if you make a solid cylinder and then make the top thinner the side walls will taper automatically without any user intervention.
so it becomes piece of piss, to rough out a 3d kite shape and then start altering things like, curve, aspect, span length for any part of the design and have the software update all interconnecting bits automatically. a basic 2d cad package like autocad doesnt do this.
ryan: i was working for a graphics hardware technology company, we plugged into every cad package, http://www.art-render.com
, (check out the speaker image in the gallery)sales and marketting in sales and marketting, you make a product, test it, get people involved in feedback, improve it and sell some more.
most big ass cad packages have 100's of plugin applications for them, you make a model export it into the wind tunnel plugin and bobs your uncle, data that bears little resemblence to the true complexity of the elastic system that is a lei kite...
some of the big guns are likely using variants of commercially available cad app's with specific plugins desinged to their needs, something like surfplan pretty much does it all.