As I mentioned in my Inspiration post, I looked to bike couriers as a fax replacement system. Here are the components of the project.
The Ardunio board was programed & wired to have an LED blink while the plastic bag is closed. Once the bag is opened, the circuit is broken & the LED shuts off. The light indicates the bag contains an important document that has not been opened yet. Once the bag is opened, it could wirelessly send a message to a database indicating that the bag has been opened.