Much like ring mail, I'd rule that studded leather has a significant amount of metal and still would not be wearable by druids. Technically the studs don't have to be metal, but realistically they would be simply because little else is as durable or effective. There is no leather armor where you can just put small studs here and there and expect those studs to do anything significant. The only historical equivalent was probably brigandine, which is basically metal armor held together by leather.
If your DM allows "other materials" why bother stopping with studded leather? Be a rules lawyer and throw on ring mail. Or just get that plate made out of a non-metal material that weighs approximately the same while being non-metallic yet formable material that can be easily reshaped. It's called "does-not-exist"ium. Or magic, of course.
In other words, sometimes there is no one true answer, ask your DM.
If your DM allows "other materials" why bother stopping with studded leather? Be a rules lawyer and throw on ring mail. Or just get that plate made out of a non-metal material that weighs approximately the same while being non-metallic yet formable material that can be easily reshaped. It's called "does-not-exist"ium. Or magic, of course.
In other words, sometimes there is no one true answer, ask your DM.