I like the idea of a fabric exchange. I would love to join.
I am in a "coupon train" that works well. Maybe some of those principles will work for this. It could be like a "fabric train"

A cool name helps

My current train has no name, but the first one I was in was "The Buck to Blue Choo Choo" since we mail from Ohio to Michigan and back. My DH thinks I am nuts!
Our train works like this:
We have a list of about 10 people. The first person on the list mails to #2, #2 to #3, #3 to #4 and so on. Eventually the train goes full circle and everyone gets a little bit from each person. What we do is add whatever coupons (in this case we would use fabric cut to a specified size) you do not need. The person who receives your envelope would take what they wanted and replace what they took with at least the same amount. We all mail on Tuesdays so everyone receives an envelope around the same day each week.
To start the train we all mailed to the person below us on the list the first week. We also check in on Tuesday after we mail, so your partner knows to expect something.
After a few weeks it was really fun to see what was coming. I always look forward to my envelope. I usually only get bills, so getting coupons in the mail makes me happy. It doesnt take much to excite me

My DH teases me that I am a cheap date since I always have a coupon.
Anyway I think something like this will work if someone could come up with the details and be in charge of the list.