Hi
FYI, feel free to refer to or check out these two"resources":

Analytic Drawing of 3D Scaffolds - http://www.autodeskresearch.com/publications/3dscaffolds
&
On Expert Performance in 3D Curve-Drawing Tasks - http://www.autodeskresearch.com/publications/3dcurvedrawing

Both come from Autodesk Research and derive from Ryan Schmidt's work there - http://www.autodeskresearch.com/people/ryanschmidt - as well as from his PhD studies at the University of Toronto's Dynamic Graphics Project Group - http://www.dgp.toronto.edu/~rms/

Cheers,

. Diego .