I have done swaps over the years. The most interesting one was in my quilt guild where I had to supply a 10" square of one fabric for each participant. The result was to be a 12" block using the starting fabric (the swap rules). The results were interesting -- the print I chose had a lot of colors and of course everyone chose their coordinating fabrics (which is what I wanted), but the resulting blocks were interesting -- not only different blocks but the size ranged from 6" to 18" with everyone having a fascinating reason for the non-12" size. Fortunately, I was not bound to make a single quilt, so I sorted the blocks to the closest size, added enough sashing so they were all the same size, added a few blocks of my own and got 2 table runners and a lap quilt. They turned out very nice and were a matching set but not identical. Turned out to be a lot of fun figuring out how to use the blocks. What was even more fun was that everyone participating in the swap had to contribute at least one block to the charity quilts we make. When enough blocks were gathered we had a sew day to assemble them (and we all got to pick which blocks we put together). Most of the blocks were orphans from quilts or classes and they were fun to see and assemble, too.