> I've often wondered how CAD manages to produce complex, detailed 3D 
> objects. I have yet to see a modeller that makes it feasible to produce 
> any moderately complex 3D shape.

Yes, but have you actually seen anyone using commercial CAD software like 
Catia or Pro/Engineer? You know, the software that people who build planes 
and cars use?

eg here is a screen shot of a model from Boeing:

http://www.nextcraft.com/media/aviation_technology/military_nasa/B737_catia_big.jpg

It's a bit more suited to doing this sort of stuff than a modeller like 3D 
Studio or Blender.  It is more focussed on dimensions and model hierarchy, 
and less on the graphical appearance (most of the time you are just using 
plane gourard shading or even wireframe if you need to see certain details).

For example, the modelling process in a CAD package for that metal case I 
posted would be something like this:
- Draw the outline cuboid shape
- Add on extrusions and cuts for any bumps and dips
- Add rounds to any edges
- Shell the model (this leaves a shell of specified thickness, 2 clicks in 
CAD)
- Add in holes where necessary
- Add more rounds
- Add in any clip geometry

The CAD software remembers all that history used to generate the model, so 
you can always go back and change the shell thickness and everything else 
updates (or move the position of a bump etc).

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