The Sony Xperia Z Ultra is unique when it comes to Android smartphones as it is the first handset where you can use pretty much anything as an input device for the display. Sony Mobile recommends pencils with a diameter >1mm, but you’re welcome to give anything else a try that maybe to hand.
The video below does just that where the screen input is tested using keys, coins, pencil and a pen. All of these fare well, with the touch sensor registering the commands as they were meant to. The diameter theory really does seem to apply though, as a Stanley knife, mechanical push pencil and ruler don’t really work. Not that we’d want to be using a Stanley knife on that gorgeous display to begin with. Check out the video below where all of these instruments are tested.