It is designed by Leanne Valiukas from Patchwork and Stitching Vol 8 No 11. (Photo from the magazine)
I did lots of calculating, measuring, alterating, joining, sewing, trimming, to make the strips into the required sizes. I then added lots of pockets (some were in the pattern, some I added myself to use up more of the blocks I had made).
And here is my finished bag: