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)
Step 2: Cut it out!
Cut out two pieces of the flat parts of the plastic container in the size/shape you want. Mine was about 3 inches x 2 inches. You could also do circles or other shapes, but you need to round off any corners because corners will get sharp when shrunk. (note: all plastic doesn't melt the same and keep the same proportions, so cut both pieces running the same way. e.g. if you're doing 2 rectangles, cut out one large rectangle and cut it in half to ensure your pieces run the same way. If you're doing circles, be sure to mark the top and put your holes in the same place.)
If there is any impressions on the plastic (like the #6 symbol, or words) you can just color over it and it will go away in the shrinking process. But be aware it may be a pain to color or draw lines over.
On each one, use a hole punch to make a hole in the top center.
Step 3: Draw your doodle, and color it!
Randomly color in the design using a variety of light colors. Colors get way more intense when shrunk. The black will smear if you touch another color to it, so be careful. Again, shrinking will hide most issues.
Alternately, draw your design on the front, and turn over the plastic. Color it on the back! You won't have to worry about smearing your black design. However, make sure you don't leave any gaps between your colors (ie, color over all the black lines!) Otherwise you'll have gaps in the color when shrunk. You could also color the whole back in one color if you want to go simple.
Step 4: Time to cook!
If your oven is already hot, this will happen almost immediately and take maybe 30 seconds to complete the process. Keep watching!
Sometimes, if you have a long skinny piece, it may turn on it's side and curl up. That's fine, just flatten it out when it's done.
Step 5: Remove from oven
If it's not quite flat at the end, you can press it down flat immediately. Note, depending on your plastic, it may not be quite the same proportions as you started with.
Step 6: Sealing - optional
You can also try painting with clear fingernail polish, several of my readers on Dabbled have said that worked for them!
Unless you want the colors to lighten considerably, don't seal with any sort of spray acrylic that contains acetone. Although, it may give you an interesting effect! (I have a whole section on that in my experiments)