Beautiful Modeler is a tool that combines the iPad with a Mac and turns it into a wonderful 3D modeling tool. I think its absolutely fantastic and a real portent of what is possible. The iPad acts as a controller and be moving and slanting the iPad you can change the orientation of your model on screen. Each model has  a set of points and you can manipulate and change these points with your fingers. This is how easy a lot of 3D modeling tools have to be are we to get everyone started with 3D printing. And yes, the output from this nifty, and open source tool, can be exported to STL and 3D  printed! I adore Beautiful Modeler by Interactive Fabrication!

Check out the video of it in action below: