I'm working on a travel tote bag that will carry a laptop & other travel necessities. The size is 15" wide x 10" tall x 8" deep.

I see punching sets like the Aiskaer Leather Stitching Punch Set, Diamond Chisel Tools, 4mm White Steel.

What helps you decide what size & shape holes you need (4mm? 5mm?) and their spacing? Is it all aesthetics or are there structural considerations I should be aware of?