1 - Install depdendancies:
sudo pip install inosudo apt-get install arduino
2 - Create/clone Marlin Respository:
git clone https://github.com/MarlinFirmware/Marlin.git
3 - Copy OctoPi Firmware Upgrade Script to root of Marlin repository
4 - Link the Marlin source files to a file named 'src': ln -sf Marlin src
5 - Create a lib directory: mkdir lib (Where libraries will go to satisfy build depdendancies
6 - Runs script to build and upload firmware to your Marlin compatible 3D printer