I made this double hide out of styrofoam and grout. I thought about adding some different color highlights, but instead liked the way it turned out without them.
There is a wall inside that seperates the 2 rooms. I cut each level out of styrofoam and glued them together using styrofoam glue. I then dug out the rest of the styrofoam on the inside to make the rooms. I also roughed up the edges so it would look more like rock than styrofoam.
After the glue dried I added two runny thin layers of grout letting it dry between each layer. The third layer of grout was a bit thicker, but still kind of runny. The fourth layer was much thicker and I probably could have stopped after that layer, but it did'nt feel heavy enough so I added one more thick layer on top of that.
Then after the grout was dry I sealed it with a grout sealant.
I used some grout that I found at a Local chain hardware store. To make the grout thin you just add more water. The less water you add to the grout the thicker the grout gets.
It was the color of the grout, it is a terracotta color, very common grout color. There are a lot of grout colors out there. I plan on making another one for my sons gecko and am planning on making that one a sandy color to match the fake rocks already in the tank.