Planning viv for tiger salamander looking for advice

[skiblits]

So I am making plans to turn my 55 gallon terrarium into a vivarium for my tiger salamander. Where can I go to find good resources as far as safe material to build a pond with and back grounds? I know they absorb toxins threw their skin so I am very weary about what I can use in this vivarium. I watched a video on how to build a water fall with pond but the guy was using foam he cut out and a hot glue gun then just painted it all covered it in a sealant. I'm worried all of this would be toxic for my Sally. Can I use some type of clay to make my pond? As far as the back wall decor I watched a video that cut it all out of foam once again then covered everything in grout. Once again my fear is whether or not this is safe for my Sally due to her sensitive skin. Any help is appreciated. Thanks everyone! Much love to you!
Skibs