DsLabs have come up with a new DIY project, which add a new physical knob. This interesting little thing  lets your iPhone touchscreen moving towards more than just touch. You can get some feedback while touching the screen.

Similar to the soft stylus, the trick is finding a way to create a conductive path from your hand to the screen. We started by using copper tape, conductive fabrics (see the soft stylus) and wires to simulate two touch points on opposite sides of the knob. It takes some careful tuning to get the touch points spaced correctly and sized such that the screen reads them as a touch, but it does work with a little patience.

Check the movie on dsLabs.