I've made them both water bottle carriers that they can sling over their shoulders, and of course, they enjoy the novelty of carrying them =) I made them with handles that are attached by crochet buttons. With the handles removed, the carriers can be used at home as hugger coasters, or, the handles can easily be replaced if they out-grow them. Why not make one for yourself for taking to the gym? Or make some for your wine bottles for whne you BYOB =)
I used yarn that knits to a 4mm needles with a 4mm and a 3.5mm hook, but you can use whatever you have available.
Techniques used (UK terminology):
- ch: chain
- dc: double crochet (US single crochet)
- slst: slip stitch
- inc: work 2 dc into next stitch
- dc2tog: insert hook into next hook, yarn over and draw through loop, insert hook into next stitch, yarn over and draw through loop, hook through all three loops
- tc: treble crochet (US double crochet)
- back loop only
- working in continuous rounds
- working rounds by joining
- working in continuous rows
With larger hook,
Round 1: Ch 2 and work 6 dc into 2nd chain from hook (or work 6 dc into a magic circle)
Round 2: 2 dc into each st round 
Round 3: (1 dc, inc) x 6 
Round 4: (2 dc, inc) x 6 
Round 5: (3 dc, inc) x 6 
Continue increasing 6 stitches per round in this manner until the circle is just bigger than the base of your bottle. Work one round using only the back loops for a nice little ridge giving the carrier more structure. Sl st to the next stitch.
Switch to working in trebles:
Switch to smaller hook, ch 3 (forms first tc of round), tc in next stitch and each sticth round, sl st to the top of the 3ch that formed the first tc.
Continue in this manner until work is approproximately 2cm shorter than you want it to finish up.
Switch to working in doubles for button-hole band:
Switch back to larger hook.
This section, because it is being worked in doubles, can be worked in continuous rounds. If you choose to turn after each round, Sl st to join the last st of the round to the first, 1ch to 'step up' to the next row height, then work the first dc of the row into the same stitch as the sl st. You will need a 4ch space for each button-hole and will need to work two button-holes spaced opposite each other.
- Work 2 rounds dc
- Dc to button-hole, 4ch while skipping 4st, dc to next button-hole, 4ch while skipping 4st, dc to end
- Dc to button-hole, work 4ch, dc to next button-hole, work 4ch, dc to end
- Work 2 rounds dc
Round 1: 2 chain then work 6 dc into the 2nd chain from hook, or work 6 dc into a magic ring
Round 2: 2 dc into each stitch round 
This is a good point to tighten the magic ring completely and weave in the end
Round 3: Work 1 round straight without shaping
Round 4: (dc2tog) x 6 
Weave through the last 6 stitches, stuff tightly with small pieces of waste yarn and pull to tighten. Keep a yarn tail for securing to handle
Work a handle of the required length in doubles or trebles and sew the buttons, one on each end.