offer the pen loop to be added later if she so desires?
It would need to be included when I go to sew it up...one set of stitches. Or even if I attached it to an interior pocket away from the seam I need to do so before the pocket is attached. It's much much easier to sew on that way.
It is possible (but really risky) to add it by means of adding a snap or rivet assembly...but then the snap or rivet will wear out over the years (if a snap isn't lost) and add a wear spot in the meantime.
I think that I've talked myself out of it...she can always just stuff a pen/pencil in one of the pockets...they are going to be tight anyway and it will help loosen them up over the years. Making them easier to use.
It's always about the feel and durability when making leather goods. (So much cheap stuff or half finished handmade is on the market) but every edge that can be touched needs rounding and finishing. No rough or sharply cut edges should ever be felt. No rawhide ever seen or felt.
This isn't like a leather tool bag pouch that's all industrial strength... although with the type of leather I'm using it will last for decades. You won't ever see this type of stuff in any bookstore or department store shelf.
I've talked to several people who do this stuff for a living...they charge what I see as outrageous prices...but since it lasts a super long time and stays nice and is custom made...they can get it....but they said to pay attention to every small detail. Leave nothing untreated and look ahead at potential problems. Your reputation can actually outlive you. (It probably won't...but it could)