http://devpost.com/software/faceboxx
Faceboxx is an open-source desktop front-end that uses Facebook Messenger as a cloud storage service. It is currently set to break the file into 10MB chunks as per the constant specified in chunk.py.
To run, execute src/gui.py and enter a username and password when prompted. Then select the "browse" button to select a file on your computer that is greater than 10MB large. Make sure that Firefox is installed in the default location on your system and that you have a working Internet connection.
Currently, the encrypted zip function uses the pyminizip library, which only works on Linux (smihica/pyminizip#3). A version that works with the 7zip commandline interface is in the works.
The script also requires the Selenium WebDriver Python library (http://docs.seleniumhq.org/projects/webdriver/).