What I've been experimenting with lately is: fusing plastic.
Basically, what you need are plastic bags, a pair of scissors, an ironing board, an iron and some parchment paper.
Place your ironing board where you have a good ventilation (there could be fumes), cut the bags into flat sheets (cut off handles, bottom and one of the side seams), sandwich three layers of plastic between parchment paper (to protect iron and ironing board), put your iron on a medium heat and keep the iron moving on the sandwiched layers for about two minutes - turn the 'sandwich' and repeat from the other side as well.
Different kind of plastic bags behave differently, so you will have to experiment a bit with the heat and the time you keep ironing. What you want to achieve is that the surface of the bags is melting to the point of being fused - without shrinking too much or producing holes in the plastic - adjust the heat accordingly.
Let your fused sheet cool down, tear off the upper parchment paper gently and decide whether to add strips of new plastic here and there for hiding holes or wrinkles, for reinforcing or just for design reasons.
About 3-6 layers of plastic are to recommend - the thickness depends on what you want to use it for.
I decided to sew a fancy wallet, or money-bag, out of my fused plastic, using a ebook-pattern I bought from 'ki-ba-doo' at DaWanda (similar to Etsy) a while ago.
The fused plastic is very durable - still you can sew it like a fabric, using velcro strips or snap fasteners for closure. I think it's quite a cool material to work with ;-) and there are certainly a lot of projects I can think of using this ...!
(German summary: In der letzten Zeit habe ich mit dem Schmelzen von Plastiksackerln experimentiert - ein cooles Material, das sich wie Stoff weiterverarbeiten läßt und gleichzeitig sehr strapazierfähig ist! Wichtig: gute Belüftung und unbedingt das Plastik zwischen Backpapier legen, um Bügeleisen und Bügelbrett zu schützen!)