Go through all your old magazines and cut out a few cool photos you would like to turn into polaroids. (you could probably try using actual photos, but be advised that your results might not be to your liking.)
Condition your white clay and roll it out with your rolling pin. (make sure not to roll it out too thin!)
Take your magazine cutout/image and lay it onto your rolled out clay. Be careful not press it into your clay!
Take your blade and start cutting out the shape of the polaroid using the magazine cutout as your guide.
Take the cutout, set it aside, and bake JUST the clay according to package directions.
After it has completely cooled, brush some triple thick onto the area where you're going to apply the image to. Be sure to smooth the image out and apply some more triple thick on the edges!
When dried, apply triple thick all over the "polaroid" to seal in your work. Add a magnet to the back and you're done!