Here is a single falling streamer crossing tiles.
Next step is to use an 18 byte array to have up to two falling streamers per column.
If you want to duplicate this, here are the components:
The boards for this project can be made at PCBWay.com:
The rest of the components are available on eBay.
Get the software for this project at GitLab:
Each tile board runs this sketch:
The first board in the chain has an extra Arduino Nano mounted on headers on the footprint marked "Nano-Prog", this Arduino runs the animation sketch and sends commands down the chain to illuminate specific LEDs.
The sketch for the master Arduino is here:
If you like this project, follow it on Hackaday.IO
Here is a new version with one falling streamer per column: