2 layers53.3 × 22.9 mm

B STM32F103-EVAL R1.0
Boardoza/Boardoza_STM32F103_Blue_Pill_Development_Board
Compact Blue Pill STM32F103C8T6-based ARM Cortex-M3 development board for versatile embedded applications.
35 parts3CC-BY-SA-4.0
KiCad boards from 3 GitHub repositories tagged “arm-cortex-m3”, the most starred first; open any of them in PCBKit.

Boardoza/Boardoza_STM32F103_Blue_Pill_Development_Board
Compact Blue Pill STM32F103C8T6-based ARM Cortex-M3 development board for versatile embedded applications.

Will946/TeaCupHotPlate
Keeps your tea at temperature by turning the circuit board itself into the heating element. Overengineered, like all good tea rituals.

choicebuilds/SumoBot-v2
A Robojackets robot (v2) built from scratch, featuring a custom 4-layer PCB, STM32-based (ARM Cortex-M3) firmware written in C (STM32CubeMX + CMake), and a 3D-printed chassis.