This instructable will show you how to make a cool 3D background that goes inside your aquarium and looks like real rock but only weighs less then a couple of pounds.
Step 1: What you need
You will need the following
Razor or Box knife
Foam cutter or maybe electric knife (both are optional)
Ruler or other sutible straight edge
Hot glue gun (optional)
Cheap paint brushes, all sizes
Tarp (optional, to keep mess at a min)
1 inch pink foam board (the kind you buy at Home Depot or Lowes)
100% Silicone for caulking gun (GE silicone 1 is what some recommend) I used the Red Devil Architectural Grade. As long as it does not contain any mold or mildew inhibitors and is 100% silicone it should be fine. The less ingrediants the better IMHO.
hot glue (optional)
Cement or cement overlay
Cement coloring (optional)
Small finishing nails
Note on pink foam: There are two types, one has a plastic cover on it (vapor barrier I think?) and the other does not. I bought the one that did not have the plastic on it. If you buy the one with the plastic on it, you will have to peel the plastic off. Also if you have access or want to buy more foam, you can buy several thickness of the stuff to help create different thick and thin layers. I just used one sheet of 1 inch stuff and glued it together to get the thickness I wanted.
Note on hot glue: I have read where some people used hot glue to glue everything together instead of silicone. It is faster and it shouldn't pose a threat to your fish. I used a combination of both, hot glue on the smaller pieces and silicone on the larger pieces. Its up to you. Trying to get hot glue to come out in the quantity I needed on some of the large pieced didnt work.