Here're a couple of flasks I've made recently. I used some denim from old jeans for the cover up and leftovers of knitting yarn to weave the "friendship bracelets", as they commonly called, for decoration pieces. Interestingly the flask with the horizontal stripe is a kind of a happy incident because I planned to make it just as the other one but I cut a piece at the wrong place, so I had to improvise. And here it is: if you messed up badly just turn it 90 degrees and the world is saved.
Flasks From Glass Bottles, Old Jeans And Yarn Scraps