The core part of the project is the rectangle screen. Screen made as a sandwich:

outer layers of it are Plexiglas sheets, inner layer is arranged LED modules. Plexigals sheets attached to each other by self adhesive Velcro strips. Wire of LED modules goes inside of Velcro strips as you can see in the photo.

I have used bare bone Atmega328 controller and programmed it with Atmel 6.1 studio with the help of AVRISP programmer. As you can see from the screenshot size of compiled program is 842 bytes. That make it eligible for the 1K byte contest.

I have used Adam Dunkels protothread library to code devices state change. I highly recommend it for any C programmer working with embedded systems.