DIY caves and ornaments with clay?

[clinton.spaceship]

i sure there is plenty of methods to design and construct ornaments for aquascaping./
I want to make little characters and random things for my FW and SW tanks,i need to know if this
ok,if it wont leak any toxins and abruptly change water conditions.
Im sure siliconing it will make it legit but have to make sure,
and if i dont have to use silicon(glossy)what other sealent can i use,...eg epoxy what not
Also is acrylic paints safe,...will be painting them


thanks alot guys any info or comments will help,want to get my tanks abit more livly character

 

[clinton.spaceship]

oh yea and the clay im using can be air dryed though it states fire between 900-1500 degrees,..
now if i air dry then bake in oven to highest(230)will it be fully bonded and cured,..safe for fish