We have had numerous challenges at our guild over many years. This year it is 5 in a Bag. Each participant makes 5 six inch 9 patch blocks, the coordinator exchanges them with another quilter, and you make a quilt using the ones you got back. We have done it with just any 5 6 inch blocks, We have also had themes. Music Titles, Self Portrait (I won 3rd place in that one) Picture This(made to depict your favorite picture. Fairy Tales, One where you used a traditional block but had to use it in 3 different sizes in the quilt.