If you can make hanging bottle vases and even hanging vases with beads from glass bottles you can of course make plastic bottle hanging vases from plastic bottles ;-)
Links:
Plastic Bottle Hanging Vase (Crea floreros colgantes) (Spanish)
via: DIY Idea – Recycled Bottle Hanging Vases
Here at unikatissima:
Hanging Bottle Vase
Hanging Vases with Beads
Entries containing the word ‘plastic bottle’