Four materials, chosen because they get better with use rather than worse.

Vegetable-tanned leather

Tanned with tree bark over three months rather than chromium over a day. It costs roughly four times as much and takes a colour instead of losing one.

Undyed British wool felt

Pressed, not woven. 5mm, dense enough to hold a shape and to stop keys rattling.

Solid brass

Machined, never plated. It arrives bright and settles to a dull brown where it is handled.

Waxed canvas

18oz, waxed in Lancashire. It stiffens in the cold and softens again against the body.