I am going to rewrite all the projects for the 30 Days in Space. I have expanded my workspace to a 2×4 sheet of plywood. You have a Raspberry Pi with a Bi Directional Logic Converter 3.3V to 5V handling the I2C bus. I have a row of Arduino devices connected to the I2C bus. I will be adding more Arduino Mega 2560 and some Arduino Nano devices to this setup.
I2C page
Inventr.io has a great 30 day project called 30 Days in Space. You are trapped on a broken space craft and need to fix it. I bought a Hero Starter Kit last year. Last month they have a deal on the $97 Mega Kit. They gave you a $40 Mega 2560 unit with it. Alex@invertr.io is working with me on this project.
I went out and bought assorted bread boards and a box of toggle switches to build my imaginary space craft. I decided to change the entire design around. I put a row of bread boards in front of the Arduino devices.