Nice long wallet pattern including a sheridan tooling pattern with celtic elements in the corners. The pattern suggests to use 3 mm thick leather. 2 mm thick leather should be the minimum for tooling. Scale it to around 19 to cm overall wallet length.
see site for many more - 1895 - Cusack's freehand ornament. A text book with chapters on elements, principles, and methods of freehand drawing, for the general use of teachers and students . by Armstrong, Charles