I would like to be able to take the schematic for the an Arduino UNO and then add an adapter for a raspberry pi hat and then wire up the i2c pins so that I can create a new hat that combines the functionality of both systems. Or I would like to take an Arduino UNO and then add a high voltage circuit that allows me to power servers and the Arduino from a battery. The point is, that I dont want to recreate the Arduino schematic from scratch. Please try to include open source projects like this so that I can stand on the shoulders of giants, and reach for the stars.