The girls and I bought a Shrink Art kit and did it one time. I have wondered since then if you can use other plastics, like this container that held grapes. Before trying this experiment I googled it, and found out that it can be done.
According to google, you can use recycled containers as well as sheets of plastic found in office supply stores, like the transparency papers.
I cut smooth plastic pieces from the container. Then we rubber stamped designs on the plastic. We turned the plastic over because the ink continued to smear. We colored the designs with sharpie markers. We found it helpful to put a piece of white paper under the plastic so we could see the design better.
Before baking and after shots.
We tried placing on a cookie sheet and baking in the sun, but it did not work. We baked them on a cookie sheet in the oven at 225 degrees for 5 minutes. Be sure to leave the oven light on so you can watch the plastic shrink up!