I have heard of the disappearing 9 Patch and and 4 Patch, but this morning I ran across A Day In May Blog and saw this Disappearing Pin Wheel Block. Hadn't seen that one before, and you can even make two different variations from it. I started to wonder how many "disappearing" blocks there were and found this listing of fifteen on Patchwork Posse. Some are offered as free patterns, some with videos. Worth checking out. I especially like the Disappearing Hour Glass tutorial from Missouri Star Quilt Company, which they have a link for you to check out.