I use aluminium mesh in my tank, they been in there for about a year without any problems, originally used them to create a riccia carpet in my tank, I now use them for a moss wall.
Have a look in my journal, first photo on page on shows you the riccia and then alonf the journal you can see the moss wall development.
After postying this question I went ahead and tied some flame moss to some aluminium mesh purchased from Halfords (used for car body repairs) ive seen no adverse effects. Only trouble is its so light so you will have to anchor it down.
The aluminium mesh is very pliable and a sheet of it could be shaped. Gives me some good ideas!!
On my shrimp tank I am going to use plastic mesh instead and see how that works, then I will replace my metal mesh with plastic in my main display, just because its easier to create, and I didn't have a lot of the metal mesh.