For a long time I've been fascinated by what this guy builds for lizards. (I'll give a link below) He uses stryrofoam for structure, loctite power grab or liquid nails to hold it together, grout in multiple layers, acrylic paint and then seals it with an acrylic sealer. I was wondering if I could use this (these) methods to build something for an aquarium? Maybe not liquid nails for gluing it together, but aquarium safe silicone. Then once it's constructed, what could be used to seal it? Would the acrylic sealer work or is there something different I could/should use? I guess I should also ask if this would work with blue styrofoam, whereas he uses the beaded white styrofoam.

Here's a sample of the work he does:

Check out his other videos to completely understand what he makes and does.