This expandable LED display for a microcontroller in Figure 1 has a simple interface with only 6 data/control wires and can be easily accommodated to a DIY design. The display has static indication.

If you need to leave someone a message, you could either entrust it to a Post-It note or you could go the slightly more obvious route and use a 12-foot long LED matrix. That's what kitesurfer did, ...