I haven't been able to work on clue #4 yet, because I'm trying to get another project finished first. A little quilt shop not so far away has introduced longarm rental. I'm planning a trip there on Wednesday to learn how to use it. If all goes well, I want to finish up a couple of projects so that I can quilt them myself over the next two weeks.
According to my calculations based on the finished quilt size that Bonnie posted, clue #4 gets us 2/3 of the way through the area of the finished quilt top. I don't know what she has planned for borders, but if the entire quilt top is made from the same sized units we've been making, we have nearly 300 left to make. When she posted clue #3, she stated that there were a couple more clues that used neutrals. Since we used neutrals in clue #4, there may be one more clue that requires neutrals. The fabric requirements state that the yellows need to contrast with the neutrals and the greens. My best guess is that we are finished with the purples, and we will be working with the yellows, greens, and neutrals for the remaining clues.
Whatever it turns out to be, I can't wait to see the finished quilt tops. So . . . off to the sewing machine to get some work done so I can get back to my mystery project.