Hi Kisa,

the epoxy raisin is completely harmless when hardened,
It is also used to make things waterproof that need to contain drinking water,
i can't imagine they would allow that when not 100% save

Here is the link of one viv build using this method,
there are more out there but this one is really good written step by step.

This is the link in Dutch:
http://www.hans-paludarium.nl/

And this one is in English
http://www.hans-paludarium.nl/index-eng.htm