I purchased two 5 meter (almost 200 inches) WS2812 addressable LED array strips. Then I seperated them into ten strips of 15 LED each about 20 inches long. Why 15 LED's? Because that is where they are soldered together at the factory. Then thew were stuck on "yard sign" material for a backing. The result is a 20 inch by 20 inch 15 by 16 LED array.
This picture shows where they are soldered together at the factory.
This picture shows the 5 volt 12 amp power supply. The array takes bout 3 amps to power it.
Here is the video demonstrating the array running the Adafruit demo.