Nice drawings of the Arduino UNO and Mega 2560 | Arduino Blog | Arduino, Embarcados
KiCad Tutorial - How to make your own Arduino Shield using KiCad - YouTube
General purpose board using Arduino MEGA PCB template, with Arduino Nano controller board, LCD+Keyboard, DS3231 RTC, NRF24L01 radio, and DS18b20 temperature sensor - Share Project - PCBWay