Here's the Video guide to make a cool mobile phone stand .
here he used a "weather-proof" lighter which gives a hotter and cleaner flame.
If you are using a conventional lighter, then you'll want to hold the plastic above the lighter, and use the heat from the rising hot gasses (and I repeat: not the flame). As long as you don't burn the plastic, there won't be any burning plastic smell.
Be safe around fire and don't set fire to yourself, your things, or other people!
WISH YOU ALL A VERY HAPPY DIWALI AND PROSPEROUS NEW YEAR!!!