It takes forever.
This was a commission during the busy Christmas season. It was a portfolio for a writer in New York.
For those interested in the process, I drew the letters on in pencil, used my scalpel and xacto knife to carve out the letters and then I tooled in the leather to the letters when I covered the board. The letters are about 1" tall and the lines of the letters needed to be slightly bigger than the thickness of my bonefolder so I could push the leather down into them.