Old tool, the bullhide bag will hold about 3 boxes loose. The round one will hold about 2 1/2 boxes loose. They are pretty good sized bags.
Are you talking about the top seam, or the front rolled edge?
Here is what I have for the inside. The bullhide, is sewn with the divider inside. The round bag, is done differently. I sewed a panel w/ gusset, and a panel with a gusset, and sewed those two, to the divider. Sort of a clamshell, if that makes sense. The round one, has a LOT of stitching, all done by hand, but is a stouter bag. The top trim is the last piece I sew, other than the belt loop.