How do people make ribcage/tooth etc necklacesT?

Question

he kind that are silhouettes of something else, they say they do it themselves, but how to they do it? And what kind of materials would you need to do it yourself at home?
Like this:
http://i2.photobucket.com/albums/y49/gemcitykitty/whitemed.jpg
http://i2.ebayimg.com/07/i/000/9d/2b/36f2_1.JPG
http://www.plastic-bat.co.uk/shopjewellery/caravansize.jpg
http://www.plastic-bat.co.uk/shop/images/products/appleblossom.JPG
http://farm1.static.flickr.com/168/483729481_6689e4c34e.jpg
Ohh and if anyone knows where to find them, please let me know. Thnx

Answer 1

You could probably make one from Shrinky Dink plastic or polymer clay (Fimo or Sculpey).

Here's a guy who sells them http://www.shopmoose.com.au/artists/view/6

And an Ebay seller http://myworld.ebay.com/gemcitystudiogirl/

.

Answer 2

looks like some sort of plastic, i suppose if you had a book showing the body parts large enough you could use shrink plastic.