Lumina® is an air-dry polymer/resin clay that does not require heat to cure. It is translucent, waterproof and dries flexible.
We posted about Lumina last April, with a short review of the translucent air-dry clay by Camille Young. Yesterday I came across this extensive review of Lumina by Mixi at Kawaii Frenzy. Mixi provides lots of photos, including a demonstration of how the light shines through very thin pieces.
Lumina is also said to be waterproof. Read the full review here: http://kawaiifrenzy.com/Blog/2010/08/lumina-clay-review/
On this page Mixi talks about experimenting with different products to color Lumina http://kawaiifrenzy.com/Blog/2010/08/lumina-clay-coloring-tutorial/
See this page to follow Mixi's experiments using Lumina in molds and testing it's flexibility (it's quite flexible when cured). http://kawaiifrenzy.com/Blog/2010/08/lumina-clay-tips-and-tricks/
I recently bought some Lumina myself, but haven't had a chance to give it a try yet. When I do, I'll be sure to share my own personal experience with it. If you've used Lumina, please tell us your own pros and cons!