I actually learned something from the most recent Project Runway episode. Contestants were asked to design fabric using TouchSmart 600 all-in-one PCs, but instead of just touching the displays with their hands they used pencils and brushes. Why does this matter? Because it’s more natural for designers who use pencils and brushes on a daily basis.
The reason this works is because the TouchSmart PC utilizes light sensors around the edge of the display to figure out where objects are on the display. As you can see in the below video, the designers made the virtual brushes the same sizes as their real brushes.