I am currently working on a new frame to make the project more adaptable. As I don't want to have too many wires to solder on my Teensy board. It's probably now time to move to LED drivers. 

Several years ago, as I was building some LED Cubes, I used to play a lot with STP16CP05 a lot. 

Those driver are very easy to use and program. Moreover, they can drive 16 outputs and you can add as many STP as you want in serial (exactly like the WS2812 RGB LED system). 

To make it work, 

• add VCC (3.3 or 5V) and a ground with a 10uF capa between them. 
• Set the OE/DM2 to ground
• Add a resistor between R-EXT and the ground (the value depends on the output current you want, see the datasheet) 
• And wire the SDI, CLK and LE signal to your control board. 
• To add a second driver wire the SDO to the SDI of the second one!

You can find a test code on the GIT of the project.