If you want to try this at home, it is a simple matter of gently heating the bags over objects.
There is a degree of plastic bag fumage, the worst lowest possible grade on the petrochemical chain, but you should never have actual smoke or you have gone too far. Wear a good quality respiratory face mask at all times and even glasses. gloves mean you can get close to the heat source. Just noticed we left the heat gun out of the picture. You will need one of these which shouldn't set you back more that $25 AUD.
Since we are launching the first products of our Plastic Fantastic exercises in Milan in April the colours of Italy inspired us.
They are watertight - so you can use them to grow a little cactus or hold a flower or plant.