Aquarium sculpture?

[thistly]

Hello, hopefully someone can help me, or point me in the right direction

The net seems filled with all sorts of contrasting info about aquarium sculpture materials in terms of safety - for both sculptor and tank inmates, ease of use, etc...
Is there something really excellent to work with that's fish safe, or would it be better to use non-fish safe materials that works best (incl paints), and poly coat it?

The reason I ask is I've been itching to start on this idea I've been sitting on for years, to make an aquarium centrepiece that looks as close as possible to this ridiculously cheesy but (I think) awesome album cover:

Would be no more than about 18" high (excl the stuff coming out the top). I guess it'd need to be siliconed into the tank.
Maybe not in browns and reds, but maybe blues and black, brown wouldn't look so hot. With a bubbler an spotlight out the top, crypts down the bottom in lieu of mosses (which I can't grow) and some suitably creepy occupants of course

 

[kallmond]

spray foam covered in concrete or even dryloc... once the spray foam cures you can carve it with a razor knife. Then coat it all with concrete, soak it for a couple weeks and there you go. Grout dye will color the concrete for you.

 

[thistly]

Excellent advice, thankyou!

 

[Goliathweb]

spray foam covered in concrete or even dryloc... once the spray foam cures you can carve it with a razor knife. Then coat it all with concrete, soak it for a couple weeks and there you go. Grout dye will color the concrete for you.

It's a good thing to proceed like this.
Soon, i do this for my centrepiece. In the center of my 170gal cube tank

Good luck, and share pics !!

++