I have presented my knitted or crocheted bangles from plastic bottles previously.
They are great and can be adapted in size.
But if you don’t want to cover them with knitting or crochet, try these plastic bottle bracelets :)
Links:
Plastic Bottle Bracelets (DIY crafts: BRACELETS recycling plastic bottles – Innova Crafts) (video)
Here at unikatissima:
Knitted/Crocheted Bangles