I am the chairperson for our guild and have done this several times over the years. We have about 50 members who actually come to the meetings and only about 20 that actually participate in the BOM. Seems it's been the same people all the time. I have found that the simpler the block is the more members make and it's often the pattern and the colors that attracts them. I give the pattern along with instructions and show the block in various stages so they can see how it's made. I have found blocks on Pinterest, Around the Block book and Missouri Star. I allow members to put their name in for every block they turn in and it's a winner take all. Winner must make at least 6 month's worth of blocks to win again. Sometimes there are lots of blocks and others only a few. When there is only 6 or so we offer them to members who make placemats for Meals on Wheels. We generally also have one block that is used for a donation quilt of some kind. It is always fun to see the finished quilts. Although it is now required many donate their finished quilts to charities.