So you would like to do more with your Teensy 3? The SmartMatrix SmartLED Shield can help. It lets you add graphics to your RGB LED Matrix Panel easily. The shield is fully assembled and doesn’t require any soldering. It has 13 I/O signals to drive the panel out to a connector.
You will be able to display graphics, patterns, and animated GIFs from a microSD card on your panel. Costs under $20 at this time.