In my setting, I have reasonably traditional Dwarves and Elves. The Dwarves magic allows them to control metals, earth, and other non living constructs. The Elves can control non sentient living things like plants and animals. They have more control over currently living things, then substances that were part of a living being and necessary for its surival (like leather), then nonessitial substances (fur and wool), finally orgainic substances that where just made by non sentient living things (silk).
The dwarves principally wear metal armor. However, metal armor is heavy and uncomfortable for day to day use, and downright chilly in the neather regions if worn naked. Since the elves can magically control plant and animal matter, the dwarves are wary of wearing cotton and wool and having dwarven soldiers strangled by their own clothing. Dwarven Leadership is looking to you for new options that keep soldiers both comfortable and alive.
Are there any options for clothing that could be comfortably worn under metal armor that never were part of a living creature? Is there any comfortable way to create metal armor so that it can be worn without anything underneath? With no better options, the dwarves will consider substances made by living creatures with a metalic base, hopeing to have an equal magic footing there. They are also open to additional potential solutions.