These charms can be used for earrings, necklaces, or whatever you'd like. They are made out of plastic recycled from a to-go container (#6 plastic). The directions below are for 2 matching ones, which could be earrings. Because plastics & pens vary, you might start out with a test piece so see how much your plastic will shrink, and how your colors come out. Or just jump right in! It's only trash.
If you want more ideas and info, I did a whole bunch of experiments on my blog:
EDIT: and I did a Christmas ornament tutorial here: Santa Shrinky Ornaments:
This was the first project I tried, and I've updated the instructions based on what I learned on the best techniques.
Step 1: Materials
Plastic: It needs to be marked #6. Many to-go containers seem to work. Look for the number inside the recycling triangle. I used salad to-go boxes from my local pizza place.
Sharpie Markers in a variety of light colors, plus black.
Toaster (or regular) oven, preheated to around 250 degrees F
Polyurethane for sealing (optional)