I covered quite a number of pads with Kangaroo leather and Hair Sheep leather.
It came/comes in thicknesses down to a .005/.007 thickness.
I bought it from Columbia Organ Leather in Columbia,Pa.
Their product is primarily targeted to the restoration of,,you guessed correctly ..pipe organ instruments.
The Kangaroo leather is incredibly soft and stretches as if rubber. Very easy to shape to the pad.
The Hair Sheep not quite as 'stretchy', but still very easy to work with especially at those thicknesses.
Kangaroo leather wasn't available in brown or maroon a few yrs back,,only white and black. Hair Sheep leather was avail in maroon and brown at that time.
Colors available for each leather vary.
(A Hair Sheep is a breed of sheep that doesn't grow 'wool' as you commonly see on them. Just a hair covering like most other mammals.)
Here's a price sheet from their website. It may be outdated as it's marked 2024.
You can order small amts/pieces as well as an entire skin.
Might be a helpful source anyway
https://columbiaorgan.com/wp-content/uploads/2024/11/COL-Price-List-2024-Complete.pdf