Both of the options has it pros n cons. The concrete mixture (I'll call it concrete couse I can't figure a better English word for it, and it shares a lot of properties) is easier to shape into natural looking rocks etc and I know it won't be harmful to digest, but it would weight a ton and I most likely would have to hire a crane to get it up on the second floor through the balcony.
The other option would be to mold it in hard plastic, but thick enough to withstand their beaks puncturing the structure, this would require more work since you can't toss the material up and shape it as you go... My thought are though that the wall isnt ment to be chewed on and we give our birds bottle cups and whatnot, allow them to play with emptied out pens etc. The benefits of making it in plastic is that it isnt as heavy, this not only means I won't have to rent a crane, it also means I can make it in larger segments (as large as I can fit through my doorway) making it more esteticly pleasing. Couse building the whole wall on location is t an option, I might want to move sometime
. Making it in bigger sections would also allow me to hide more stuff behind it like watercontainers pumps etc and be able to incorporate water into the build wich would be pretty cool. But as mentioned I would love to hear others reasoning that isn't ontop of the drawing board, trying to figure everything out. Btw the method for making the mold would most likely be done by building it all in clay and then use (can't figure the name for it but the white powdery stuff you make figurines off with children) to make a mold, remove the clay and do the finishing touches to the mold, then mold it and brake the "plaster" off of the plastic. Woulda loved to make a reusable silicone mold but hey not sure how safe that would be to the end product hehe
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