I make plabric with my plastic bags. What you do is take your plastic bags and cut the handles and bottoms off.
Next, you put two cut bags on top of eachother and put them in between two pieces of parchment or wax paper. You then turn on your iron to a medium setting and run it over the plastic bags until you see that they have fused. Make sure to do this in a well ventilated area though because it can get a little smelly