The last time I covered a pouch board with a sheet of leather (the
holes were too closely spaced for circles) I worked my way across,
applying three or four rows worth of hot glue and then dishing with
my fingers as I went.  I don't know how either the factory or pros
do it, but stretching seems like a bad idea for the leather to
remain airtight.

Roger Wiegand
Wayland, Massachusetts, USA