I used a pinking blade to trim the edges of this small zippered pouch. 
Detail of my fused plastic bags. I recommend fusing at least eight layers together.My DIL told me a good friend of hers was making purses out of plastic bags. Plastic bags? Yes. She fused them together to make 'fabric.' A Google search yielded tons of tutorials on the process.
Above is my prototype bag. If you'd like to try this, make sure to:
1. Use several layers of plastic bags so your 'fabric' will have some heft. The bags will stick together once heated without you having to add an actual fusing product like Wonder Under or Misty Fuse.
2. Make sure to use parchment paper above and below your bags to protect your iron. If you do accidently get a bit of plastic stuck to your iron don't panic. It will peel right off when the iron is cold.
3. The bags are slippery to sew. I recommend using an even-feed foot.
Note: Betsy asked whether the fusing gave off fumes. Since I have virtually no sense of smell, I'm at a great disadvantage to answer this completely. I noticed nothing that bothered my asthma. One of the tutorials found on Google may have more information.
