The pattern is called Unbeweaveable. It uses the X block ruler. It wasn't difficult. It was time consuming. I probably have 40 hours in it including the quilting and binding. Cutting took time. If I remember correctly, there are 530 black squares. Mine was king size but with this pattern you cut the same number of pieces no matter whether you make a lap or a king. The difference is the size of the X block ruler you choose. It was fun and I love the result. I may have trouble giving this one away.