2 layers

Arduino PCB Design
Gathitu/Arduino_PCB_Design
Electrical Design of a custom Arduino board out of an Atmega328P microcontroller chip
32 parts
Open-source boards designed in KiCad by Gathitu on GitHub, from 1 repository. A board’s address here is its repository’s there.

Gathitu/Arduino_PCB_Design
Electrical Design of a custom Arduino board out of an Atmega328P microcontroller chip