I have made a similar one (because I saw THAT one). The easiest way to do it is to cut the blocks in half diagonally. You will lose some of your points in the process to the seam allowance, but if you are using busy fabrics, you really don't notice it at all. Make the sashing strips whole and cut off the extra.
When I first did mine, I used extra whole blocks with the intention of cutting them down after to allow for the seam allowance so I didn't lose my points. I got distracted when squaring it up at the end and cut a row too soon in both length and width. What a pain ripping out and resewing. I put it away for a long time because it depressed me so! I ended up cutting the blocks in half diagonally at the end. I would have finished it a year sooner if I had just done that in the first place!
Here's mine...I love it, it's one of my favorites!
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