Shrink art, also known as shrink plastic, begins as a thin sheet of polystyrene plastic, rougher on one side than the other. The plastic shrinks and thickens when baked, resulting in a hard plastic object approximately half its original size. Designs drawn upon it with markers or colored pencils before baking become brighter as the plastic shrinks, allowing you to make decorative charms, ornaments or refrigerator magnets designed any way you like.
Planning Your Project Design
Once you draw on the shrink-art plastic, your pen or marker doodles stay there, so it's important to plan your design ahead of time. Whip up a template by drawing a design on paper or by printing out a clip-art image to trace onto the shrink art. Keep in mind that the polystyrene sheet shrinks significantly from baking, so your final project piece may be approximately half its original size.
Coloring Your Creations
The rough side of the shrink art is the side receptive to ink or colored pencils. If your shrink art has no rough side, scuff up one side with a piece of fine sandpaper; then wipe off the dust with a rag or paper towel. Place the paper image you wish to trace under the smooth side of the shrink plastic if you are tracing an image. Trace or draw your the design with colored pencils or permanent markers; water-soluble marker ink won't do. Color in all areas you wish to tint, as all coloring must be done before baking the piece.
Shapes and Sharp Edges
Cut the shrink art out with scissors after you color your design. Trim sharp edges to make them more rounded to help prevent the plastic from breaking after baking. If your object requires a hole -- for instance, if you're making a hanging ornament or key-chain adornment -- punch the hole before baking with a small hole punch. The hole shrinks with baking, also.
Heat It Up
Place a piece of cardboard or parchment paper on a baking sheet to bake the shrink art; many brands recommend that you do so instead of placing the plastic on bare metal. To shrink your creations, preheat the oven to between 300 and 350 Fahrenheit; exact temperature may vary by brand of shrink art. Place your cutout creations on the baking sheet and bake them for 2 to 4 minutes, watching them through the window in the oven, or by opening the oven door to peek inside, to determine when they have shrunk. The plastic wriggles and warps as it shrinks and may fold over onto itself. If you spot this happening, separate the folded edge with a roasting fork or similar tool designated for craft use only. Wear oven mitts to take the baking sheet out of the oven and allow the shrunken creations to cool for at least 10 minutes before touching. The items will be hard and cool when ready to handle.