Ruler 3 iPhone 13 Case by Michael Harrison - Pixels
The Clever Lindlund Ruler Measures the Digital and Physical Worlds | WIRED
Derek Kessler on Twitter: "I was inspired by @donttrythis's forearm ruler tattoo and made a measuring wallpaper for iPhone X & XS. Inches on the left side, metric on the right, both
The Best Ruler Tool Apps
How to use your iPhone or Android phone as a ruler | TechRadar