I have amazingly, brilliant ideas...really I do! And then they turn to crap when I make them. Boo.
This hat was several versions in the making, but I finally have the end product.
Here it is!
I started by cutting the tetris shapes out from graph paper, and fitting them together to make a band.
Then I drew the whole thing out so that when my kids mucked up the little paper pieces, I wouldn't forget how it looked. Also I colored the pieces in so I could see if there were too many of the same color together.
Then I drew out just a part of it, so that each square was one stitch, and I could remember how many stitiches to do for each piece.
Putting the pieces together was hell. I tried crocheting around each piece in black so they'd stand out, but ripped that out when I realized how much extra size was added to each piece, and that they wouldn't fit together well. Finally I settled on laying them flat and sewing them together on the back. To provide the black borders, I remembered how my mother-in-law taught me to "stitch in the ditch" when I was learning to quilt from her. So that's how the outlining was done.
Once I stopped ripping stuff apart, I took maybe 3-4 days of on-and-off work to complete it. It was painful, but I'm mostly happy with the results.