Two different guilds--joined the "Bag Ladies" and the "Tinners". Same concept. You put your preferred fabrics in a container and specify what size block you want. Each month you get someone else's bag/tin and yours goes somewhere else. Other fabrics can be added by the block maker. At the end of 12 months there is The Big Reveal. I did my very best to make interesting, properly sized, well constructed blocks for the bags/tins that came my way. Sure wish the other members would have been as considerate about my bag/tin. They are still UFO's in my sewing room. Don't want to deal with the pain of wasted fabric or the headache of crappy blocks.