That was an interesting podcast! I agree about experimenting with different materials, and I too love natural wood varieties. What I'd love to see is a wood "sheet" for a keyboard top (like instead of layering acrylic, bolt on a shaped piece of wood at the top of the case as a cover), something fairly dense with nice figure, and carved or burned with designs. Or a fully carved wooden case made of 2 parts.
Random samples from google image search (doesn't need to be that intricate, but just illustrating the endless possibilities):
Add colorful stains, like blue or black/gray, and various oils and finishes.
Alternatively, tooled leather bolted on at the top with some aged looking bolts.