Originally Posted by DanTwoLakes
Here's a no sew method for doing door panels. These door panels had sewing on them, but you don't have to sew them at all. You can make any design you want with this method.CLICK HERE
A most interesting and informative thread.
One of the last posts about oblong holes for the plastic GM clips had good info in it about using a round punch and sheetrock knife.
IIRC, Tandy Leather, has several sizes of oblong punches. And may be able to find one at McMaster Carr.
I may be wrong, but I've seen them somewhere, in varying sizes up to about 3/8"x3/4" or 1"