Materials:

plastic bottles
primer
paint spray in color of choice (I used golden and black), choose one designed to work on plastic
craft scissors
tape

Instructions:

Make sure the bottles are clean and dry

Cut the top of the bottle

Add tape around the rim so you avoid scratching yourself when filling the vase with flowers. Make sure you use strong tape.

Prep the bottles for painting by spreading some primer.

Spray paint the bottle and leave to dry. If you choose to make a pattern as I did, spray the main color first, leave to completely dry as indicated on the spray, add tape above the area where you want to add the second color, then spray the second color and leave to dry completely. I find it useful to remove the tape a few minutes after I added the second color otherwise the paint might chip when the tape is removed.

source: Plastic Flower Vase DIY | Easy Peasy Creative Ideas