Todd Ham reports: [edited]
I started with a few sketches then worked my way towards a rough 3D mesh of the device. I kept the band simple with a curved touchscreen display on the front. For physical controls I placed a single button on the left to act as the home button, and two more on the other side for volume controls.
For the lock screen I designed a simple black & white interface displaying the time, date, and button to activate Siri. From here the possible actions are: tap to use Siri, swipe up to unlock, or pull down to view notifications. Sound familiar?
The springboard has four app icons vertically stacked with a page controller on the right. Swiping up or down moves between pages of apps. Pressing the home button takes you back to the lockscreen.