This is a really neat idea. Meet-up with locals to swap the cool clothes you no longer want or need. Here's the link to find one (or start one) in your area.
I know I was blowing through sizes so fast I barely wore an outfit more than a month. Started at a tight 28 jeans, now 4.
Some other things to do with your clothes:
Freecycle
Dress for Success
National Thrift Store Directory
If you have a weekly/monthly post weight loss surgery support group through your surgeon start a swap after the meeting.
or you can get crafty and make stuff:
Coin Purse #1
Coin Purse #2
Clothespin Bag
Cupcake Bag
Be sure to snip off the buttons too. They make the greatest math counters. Kids can sort by color, size, type, amount of holes. Just be sure they are past the putting things in there mouth or up there nose stage. Older children can pick out a button from your collection and write a story about it. I spent hours and hours sorting my Mum's button box. When I was teaching I loved to bring it in to share with my class and read this book.
