Here is a picture of the new 16 digit board using the Common Anode (CA) in parallel with Common Cathode (CC) technique.

Here is a schematic for a 4 digit board using only 10 IO pins. Each additional pair of digits will only cost 1 pin. 

Read more about it at:

https://arduinoenigma.blogspot.com/2020/08/7-segment-led-board-now-drives-16-leds.html