A while back I came across this manipulator and thought you'd enjoy knowing about it.

The first link is there simply for your info; take special note on the second, towards the bottom portion of the web-page, where it makes reference to the Kite Geometry Manipulator:
http://www.ds.arch.tue.nl/Research/Projects/E3DAD/
http://www.win.tue.nl/~spranovi/research.htm

Cheers,

- Diego -