Hello ! I unfortunately do not speak English.
I hope my pictures can help you.
Sorry...
Necessary stuff:
-2cm styrofoam
-silicone adhesive
-flexible tile adhesive
-gypsum
-two-component resin
-brushes
-mosquito net
-brown powder
-cutter
-heat gun
-some fans for drying
-soldering gun
-sponge
DESIGN (first instance):
Using: silicone, soldering gun, cutter, 2cm styrofoam
Compilation principles: 
MOLDING:
Using: cutter, soldering gun
ROUNDING:
Using: flexible tile adhesive, mosquito net, brushes, fans
3 COATS flexible tile adhesive and coloring:
Using: flexible tile adhesive, fans, brown powder, rushes
AFTER DRYING: 
Third layer grooming: 
Dither green spirulina tablette and minimal water:
Using: sponge
Last step. Resin coating.
Using: two-component resin, brushes
Too light weight...
Fixing the aquarium:
-stones glued to the bottom
or
-bottom of the tank foam adhesive strip
Full photos galery:
https://picasaweb.google.com/1162582...CP2AmqiR6cLfEg
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
Two instance: 
https://picasaweb.google.com/1162582...CNSA2sWHz_-pOw
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
Tree instance: Compilation principles: 
