How to: Make a Cheap 3D Aquarium Background

So while finishing up some other projects in my garage. I need to slow down and do another Day One aquascaping project. This time I will be making a
3D aquarium background.
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Material needed for this project:
-Styrofoam 1inch thick or thicker much better
-Silicone sealant
-Box Cutter
-Cement
-Cement Dye
-Sahara water proofing compound (or you can use your local water proofing products, I used this brand because it's 3x cheaper than the rest of waterproofing products)
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