I just returned from Thanksgiving in LA with my brother, product development
director for Giant Bicycle.  He was showing me how they can now take
aluminum tubing for frames and blow it into a mold using oil pressure.  They
even have some tubing with a double internal wall that they can then
partially split at one end to form the top tube and diagonal tube all as one
piece, very trick looking.  The tubes now develop very trick aero shapes,
tapered and all.  I couldn't help but think that a propellor blade couldn't
be made with this same concept.  Too bad they don't make prop blades, they
make some bikes frames for $3-4 a piece!
    The CAD systems nowadays compared to what I used to write for
McDonnell-Douglas(20 yrs ago) blew me away.  A few keystrokes and a round
tube insects with a airfloil-shaped tube in seconds.  These kids nowadays
don't know how easy they have it :-)  (what? parametric cubic patch?)
kevin