My mini-group is doing a round robin. That's when each of us supplies a center block and each block makes the rounds of every person in the group. Each time a block comes to each person, that person adds a border of some kind to the project. We just got our first block this week, and mine was this 30's panel of a child in a bunny suit. Of course I have NO 30's fabrics in my stash, so I had to make do with what I had. 30's colors are very distinct and hard to match without going to reproductions. I got a close red and purple, but the green I chose, whike the right shade, is too pale, and the yellow a bit too bright, but those things weren't so obvious until it was all pieced and together.
I made the hourglass blocks in the border of course, using a black and white print for my background and 4 colors for the hourglasses. Despite the 'wrong colors', I'm not re-doing it. I hope it works out okay as it goes on to the next person, who has to build on what I've done.