I think I nailed it, but I also dig JudoP's design in this thread. I've also discovered a new natural cord combination that I think has a lot of potential, which I will use with this leather pouch. To be continued.

Well done!

I think I know what you're talking about.  If you look through the first 5 pages or so in the Pictures of Slings thread, there are a number of examples that fit your description: https://slinging.org/forum/YaBB.pl?num=1172017416.  If you take a look and find a specific one, we can probably help you layout a pattern if you need.

I was encouraged to post some photos in the par of the forum. The diagram for this pouch is marked up by 1 cm. A cardboard cut-out makes it easier to transfer the diagram to a piece of suede. A small part of the pointy corners has to be trimmed for the flaps to meet when putting the pouch together. Before punching sewing holes, one has put on a thin line of contact-glue along the edge of the flaps to keep the flaps in place while punching the sewing-holes and doing the sewing. The big holes along the canal are optional. They make the pouch more flexible at release of the projectile. I had difficulties deciding what is best, holes along the canals or not. Then I came upon fixing the pouch to the cords by a couple of knots in the holes near the ends of the pouch. The pouch without canal-holes has to be fixed to the cord with a little double-half stitch on the 4 corners. Bending and attaching the flaps to the center makes the whole pouch curve a little in a natural way keeping the projectile in the pouch until release.
The double cord has the advantage that the pouch does not easily tilt and drop the projectile before slinging.
The rubber balls are soft like jelly but holds together even if thrown hard. Unfortunately, I have no brand name, a friend found the balls for me in another part of Denmark….

I searched for Goliath files, couldn't find anything.....

Interesting - thanks !

Can you elaborate on what you're looking at?  I don't see anything with the sling pouch that I would describe as asymmetrical.

This design wasn't changed as far as I know.  I received one of these slings from CA a little while back.  If needed, you can make any adjustments to it you would like.  That's one of the big benefits of leather pouch templates.  If you need to make an adjustment to suit your needs, you can.

leather pouch temp. for Acro LD-1/LP-4 on millimeter paper