Clacks were spontaneously proposed by a friend as a project for 39c3 when I was looking for something to work on for the event. I right away thought it was a great fit: it blinks, it moves, it makes noise and it's interactive. On top of all that, we are both fans of Sir Terry Pratchett and were excited to see a Discworld project at congress.

The current version only broadcasts messages that people send to it via a web interface and doesn't actually communicate between nodes. The reason for this is twofold: I wanted to keep the scope from creeping and pointing cameras at people at congress for doing computer-vision–based communication between two nodes is generally not a great idea. We are considering expanding upon the existing project for EMF and making it communicate.

Unlikely as it is, someone had the exact same idea this congress and built their own interpretation of clacks as well. Here is their project page and here is mine.