qmk_firmware/keyboards/the_ruler/readme.md

The Ruler PCB

A custom keyboard PCB ruler, that can also function as a macro pad

Keyboard Maintainer: Maple Computing
Hardware Supported: PCB Ruler V1 by That-Canadian and Bishop Keyboards
Hardware Availability: https://www.maple-computing.com/products/pcb-ruler-v1-1

Make example for this keyboard (after setting up your build environment):

make the_ruler:default

See build environment setup then the make instructions for more information.