Here’s another quick hack to add more physicality to touch screen displays. Using a small to medium sized knob, you can modify it (or even use it by itself) to behave as a rotary input.
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.
Alternatively, with a small knob, it’s natural to grab it such that your fingers actually touch the screen making it nothing more than a physical prop to provide some tactile feedback (as shown in the video). It works great and doesn’t require much in terms of materials or time; just grab a small object and give it a try!