Hey folks,
I've got tons of questions on scale liners can you help out?

First, what I think I know.
1) The liner seems to be predominantly to increase strength of the scales. When working with thin scale material, or something that might bow/bend/warp, having a metal backing will help keep it straight and from cracking.

2) The liner also seems to be for aesthetics, or for higher end razors, as it adds a two-tone color, and involves more worth & materials.

3) The liner can provide a foundation for using multiple pieces of scale material for each side of the razor.

Now, for the questions:
i) If you're creating a liner for stability, how do you know if your scales are prone to warp/bend? If they are really thin, or based on the material? Like does horn warp more likely than wood, or certain types of wood warp more often?
ii) How thick should the metal liner material be? I don't want anything too hard to cut/work with.
iii) If you're creating a liner for aesthetics, I guess you could add one to anything. So why do you cover it with a layer of plastic so you don't see it on the inside of the scales? Is this just to protect the metal from rusting?
iii) Where can you get the plastic to line the metal liner? Are there other options to cover the liner with besides plastic?