I had a feeling that copper would not be good since it can be reactive with even acid foods. Just trying to come up with a more decorative material for a playstand than PVC, but then I guess that there's a good reason why that is what is so commonly used. I have some really nice citrus branches in my yard that will be perfect for inside of the cage and also for the playstand. Thank you again for your response. Brass is sometimes used in toys.
Steel is the prefered choice whenever possible.
Since citrus is a fairly common tree, it is most likey it would be listed if it were problem.