It's been suggested that this could also be a good basis for a wash bag/make-up bag. I haven't tried that yet. If I was to do that I would line it in a waterproof fabric (buying a shower curtain on sale, or stripping an umbrella that broke in the wind, are quick ways to get this type of fabric, by the way).
I offered to make a tutorial "if anyone wanted" on the forums and yep, somebody wanted :) So here we go.
This tutorial is for a simple unlined bag, I made a lined bag but it was a bit of a PITA and I honestly don't need them to be lined, although it is nicer it wasn't worth the extra effort. (That said I usually line the bags I sew, and have no problems with it, so I might figure it out later.)
This tutorial does not explain the terminology nor how to sew in a zipper - google is your friend. :)
Right then, let's get to it.