DIY Sculpted hides & decor?

Are there any gerbil safe sculpting options? I know polymer clay and air dry clay are no-nos, but what about paper clay or like paper mache? I just want to make something a little more customized for my gerbs with something other than cardboard.

As an additional question, can I use water-based paints to paint decor? If not, are there any safe paints? I tried searching but can't find clear answers. Thanks in advance!