Inner Door Liner Replacement

[Subcooling]

I have two Cavalier machines one is a CSS-141F and the other is CSS-12-141.  Both are very similar and seem to be a bit of an odd-ball model. And as it happens, both need to have the inner door liner replaced.  I am not finding a replacement, so I was wondering if anyone has used a different material to fabricate a new inner door liner.  Galvanized or stainless sheet metal? I also read that fiberglass reinforced plastic might be good. If anyone has experience with this or an educated opinion I would appreciate your feedback.