I used Cotton Yarn for this water bottle bag. Measure the first circle that you make to determine if your gauge is the same as mine. I realize that the hook size that i have used is smaller than what is normally used for worsted weight yarn. I recommend cotton as there is less stretch. This bag is made using two circles for a reinforced base and then working upward. it is made all in one piece except for the first circle. You can make the strap smaller if you are making it for a child. Strap size will be determined by you.
You’ll need about 2.5oz ball of cotton yarn.