Sta.sh
I've been really curious about this tecnique shared by *Shacchan - see this journal for the instructions - and finally today I've managed to give it a try
It was fun, althought a little messy. I just need to try some more to find the perfect dosages!
Step 1
I mixed some light brown clay with about an half of water and an half of Fimo liquid, until I got a creamy thing (as Shacchan explained, it should look like a glaze). Then, I added the baking powder to the clay, proportion as shown, and mixed them:
Step 2
I made a baking tin with an aluminium foil (I didn't have anything to wrap the aluminium around, that's why it looks so weird!
) and poured the clay in it (well, I poured it all over my worktop too! 
). I baked for about 10 minutes.
Step 3
This is what the clay looks like, after it's baked. Gotta admit it looks anything but good 
Step 4
The big moment! Seems like it worked - but I'm thinking of using a little more powder next time, to get a bigger texture.
Step 5
I painted the slice with acrilyc paints for a more 3d look. Oh yes I desperately need to improve my painting skills!
Done!
Thanks again to *Shacchan for the super-useful tips! Can't wait to try this out again 
Stellaskin design and graphics by ~thinkpastel
Artistic 
Let me know
i tried to do it by mixing polymer clay and water with backing powder<and this is the result
[link]
what do u think
I hav 2 go try it now
Anyway, when I guess the right dosage, after baking the outside of the clay is smooth and somewhat shiny, while the inner part is very "light" and kind of crumbly. Hope this helps!
By the way - thanks for subbmiting this tutorial... I would never ever get the idea of making this that way. And - this toast looks so delicious.