Saw a necktie water bottle sling tutorial posted on the Internet and thought I would try it. Well, I tried to do it from memory and completely got it wrong but ended with my own different technique. Check out the Betz White link above or my tutorial below and make your own.
Place a water bottle down on two ties, as shown. Figure out how high you would like the tie to be on the bottle height. The bottle is more secure with a higher span.
Stitch a square base. I cut a square shape from a hard plastic expired gift card and inserted between the two ties to stabilize the base.
Straight stitch the 2 open sides. You won't be able to stitch all the way down the base so start a 1/4" from the bottom and stitch toward the broad tie points.