I made the frog shower curtain that I purchased at the op shop last week into a swimming bag for my son. The drawstring used to be the inside tie of a pair of shorts.
I have a lot of shower curtain left, so I can make something else if not more frog bags! The shower curtain, I believe, has not been used, its in perfect condition, but was not purchased in a wrapper. I've given it a good clean anyway, and used a little to make some more reusable food wraps out of some car fabric I purchased in another op shop this week.